Systems and devices for detecting coronary artery disease using magnetic field maps

ABSTRACT

In an aspect, the present disclosure provides a method comprising: (a) identifying a first negative and positive electromagnetic dipoles in a first electromagnetic field map associated with a heart of the individual at a first time; (b) identifying a second negative and positive electromagnetic dipoles in a second electromagnetic field map associated with the heart of the individual at a second time; (c) determining a first angle based on the first negative and positive electromagnetic dipoles; (d) determining a second angle based on the second negative and positive electromagnetic dipoles; and (e) determining a presence, an absence, or a likelihood of coronary artery disease in the individual, based at least in part on (i) whether the first angle differs from the second angle by at least 100 degrees, or (ii) whether there is a presence of a third electromagnetic dipole in the first or the second electromagnetic field map.

CROSS-REFERENCE

This application is a continuation of International Application No. PCT/US2021/034269, filed May 26, 2021, which claims the benefit of U.S. Provisional Pat. Application No. 63/030,536, filed May 27, 2020, each of which is incorporated by reference herein in its entirety.

BACKGROUND

Dynamic magnetic fields are associated with certain mammalian tissue, for example, tissue with action-potential driven physiology. Changes in the structure or function of certain tissue can be reflected in a change of the magnetic field(s) associated with and/or generated by the tissue.

SUMMARY

Described herein are systems, devices, and methods for sensing a magnetic field such as an electromagnetic field (“EMF”) or a magnetocardiogram (“MCG”) associated with a tissue of an individual, a portion of a body of an individual, and/or an entire body of an individual. Non-limiting examples of tissue for which a magnetic field is associated and sensed using the systems, devices, and methods described herein include blood, bone, lymph, CSF, and organs including the heart, lungs, liver, kidneys, and skin. In some embodiments, the devices and systems described herein sense a magnetic field signal associated with a portion of a body of an individual, such as, for example a torso of an individual, or a magnetic field associated with the entire body of the individual.

Described herein is a device for sensing magnetic field data associated with an individual, comprising: a movable base unit; an arm having a proximal end and a distal end, the proximal end being movably coupled to the moveable base unit so that the arm moves relative to the movable base unit with at least one degree of freedom; an array of one or more optically pumped magnetometer(s) coupled to the distal end of the arm, the optically pumped magnetometer array configured to sense the magnetic field associated with the individual. In some embodiments, the device comprises a shield configured to attenuate a magnetic field or fields associated with an environment. In some embodiments, the shield is configured to contain a portion of a body of the individual which is associated with the magnetic field data. In some embodiments, the portion of the body of the individual which is associated with the magnetic field is the chest of the individual. In some embodiments, the arm of the device or a system comprises a joint about which the arm is configured to articulate. In some embodiments, the optically pumped magnetometer array is movably coupled to the distal end so that the optically pumped magnetometer moves relative to the arm with at least one degree of freedom. In some embodiments, the optically pumped magnetometer is part of an array. In some embodiments, the array is arranged to conform to a specific portion of a body of the individual. In some embodiments, the device comprises a processor and a non-transitory computer readable media including a computer program configured to cause the processor to: receive the magnetic field data that is sensed by the optically pumped magnetometer; and filter the magnetic field data. In some embodiments, the device comprises a gradiometer wherein the computer program causes the processor to filter the data by cancelling out a magnetic field associated with an environment. In some embodiments, the computer program causes the processor to filter the data by subtracting a frequency-based measurement from the magnetic field data. In some embodiments, the computer program causes the processor to generate a visual representation of the magnetic field data comprising a waveform.

Also described herein is a method for sensing magnetic field data associated with an individual, comprising: positioning a mobile electromagnetic sensing device within proximity to the individual; positioning an arm of the mobile electromagnetic sensing device that is coupled to a base unit within proximity to optically pumped magnetometer within proximity to a portion of a body of the individual associated with the magnetic field data; and sensing the magnetic field data. In some embodiments, the method comprises shielding at least a portion of the individual from a magnetic field associated with an environment. In some embodiments, the shield is configured to contain the portion of the body of the individual which is associated with the magnetic field data. In some embodiments, the portion of the body of the individual which is associated with the magnetic field is a chest of the individual. In some embodiments, the arm of the device or a system comprises a joint about which the arm is configured to articulate. In some embodiments, the optically pumped magnetometer is movably coupled to the arm so that the optically pumped magnetometer moves relative to the arm with at least one degree of freedom. In some embodiments, the optically pumped magnetometer is part of an array. In some embodiments, the array is arranged to conform to a specific portion of a body of the individual.

In some embodiments, the method comprises generating a visual representation of the magnetic field data comprising a waveform. In some embodiments, the method comprises generating a visual representation of the magnetic field data comprising a two dimensional cubic interpolation between two or more sensors in a magnetometer array for each timestamp of recorded data. In some embodiments, a visual representation includes color values that are associated with magnetic field values displayed in two dimensional (2D) space. Playback of successive visual representations of the sensed magnetic field data, in some embodiments, comprises a dynamic 2D animation summarizing electromagnetic activity detected from an individual.

Also described herein is a system for determining a likelihood of a presence of coronary artery disease in an individual, comprising: (1) a sensing device configured to sense a magnetic field associated with an individual, wherein the device comprises: a movable base unit; an arm having a proximal end and a distal end, the proximal end being coupled to the moveable base unit by a first joint, the first joint configured so that the arm moves relative to the movable base unit with at least one degree of freedom; and an array of one or more optically pumped magnetometers coupled to the distal end of the arm, the array of one or more optically pumped magnetometers configured to sense the magnetic field associated with the individual; and (2) a non-transitory computer readable medium encoded with a computer program comprising instructions executable by a processor configured to cause the processor to: receive, from the sensing device, a first magnetic field associated with a heart of the individual at a first time; generate a first electromagnetic field map based on the first magnetic field associated with the heart of the individual at the first time; identify a first negative electromagnetic dipole and a first positive electromagnetic dipole in the first electromagnetic field map; receive, from the sensing device, a second magnetic field associated with the heart of the individual at a second time; generate a second electromagnetic field map based on the second magnetic field associated with the heart of the individual at the second time; identify a second negative electromagnetic dipole and a second positive electromagnetic dipole in the second electromagnetic field map; determine a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole, and a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; and determine that there is the likelihood of the presence of the coronary artery disease in the individual if the first angle differs from the second angle by at least 100 degrees or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.

In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia. In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia with associated epicardial coronary artery disease. In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia without associated epicardial coronary artery disease. In some embodiments, the sensing device comprises a shield configured to shield the device from one or more environmental magnetic fields. In some embodiments, the shield is configured to at least partially enclose a portion of a body of the individual which is associated with the magnetic field. In some embodiments, the portion of the body of the individual which is associated with the magnetic field is at least a portion of a chest of the individual. In some embodiments, the shield comprises two or more layers. In some embodiments, each of the two or more layers has a thickness of from 0.1 to 10 millimeters. In some embodiments, the shield comprises permalloy or mumetal. In some embodiments, the arm comprises a proximal segment and a distal segment, and wherein a second joint is positioned between the proximal segment and the distal segment and is configured so that the distal segment articulates relative to the proximal segment. In some embodiments, the array of one or more optically pumped magnetometers is movably coupled to the distal end of the arm so that the array of the one or more optically pumped magnetometers moves relative to the arm with at least one degree of freedom. In some embodiments, the array of one or more optically pumped magnetometers comprises at least three optically pumped magnetometers. In some embodiments, the array of one or more optically pumped magnetometers is arranged to match a generalized contour of a portion of a body of the individual.

In some embodiments, the computer program comprises instructions configured to cause the processor to further filter a sensed magnetic field. In some embodiments, the system further comprises a gradiometer, and the computer program comprises instructions configured to cause the processor to filter the sensed magnetic field by cancelling out a magnetic field sensed by the gradiometer. In some embodiments, the computer program comprises instructions configured to cause the processor to filter the sensed magnetic field by subtracting a frequency-based measurement from the magnetic field. In some embodiments, the computer program comprises instructions configured to cause the processor to further generate a visual representation of the magnetic field comprising a waveform.

In some embodiments, the computer program comprises instructions configured to cause the processor to further determine the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on (iii) a parameter selected from the group consisting of: dipole parameters, integrated MCD parameters, integrated ECD parameters, mean PCD parameters, isointegral parameters, field map correlation parameters, R_peak pegged dipole parameters, pseudo current arrow parameters, extrema circle parameters, phase space embedding parameters using delta coordinates, and phase space embedding parameters using time delay coordinates, or (iv) a visualization selected from the group consisting of: a STAG plot, a T_peak MFM plot, a field map animation, pseudo current density arrows, an MCD plot, and an ECD plot.

In some embodiments, the computer program comprises instructions configured to cause the processor to further determine the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on the parameter.

In some embodiments, the computer program comprises instructions configured to cause the processor to further determine the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on the visualization.

In some embodiments, the presence of the coronary artery disease in the individual is determined based on a presence of at least one abnormality from among (i) whether the first angle differs from the second angle by at least 100 degrees, (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map, (iii) the parameter, and (iv) the visualization.

In some embodiments, the presence of the coronary artery disease in the individual is determined based on a presence of at least two abnormalities from among (i) whether the first angle differs from the second angle by at least 100 degrees, (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map, (iii) the parameter, and (iv) the visualization.

Also described herein is a method for determining a likelihood of a presence of coronary artery disease in an individual, the method comprising: positioning a mobile electromagnetic sensing device within proximity to the individual; positioning an arm of the mobile electromagnetic sensing device that is coupled to an array of one or more optically pumped magnetometers within proximity to a heart of the individual; receiving, from the mobile electromagnetic sensing device, a first magnetic field associated with the heart of the individual at a first time; generating a first electromagnetic field map based on the first magnetic field associated with the heart of the individual at the first time; identifying a first negative electromagnetic dipole and a first positive electromagnetic dipole in the first electromagnetic field map; receiving, from the mobile electromagnetic sensing device, a second magnetic field associated with the heart of the individual at a second time; generating a second electromagnetic field map based on the second magnetic field associated with the heart of the individual at the second time; identifying a second negative electromagnetic dipole and a second positive electromagnetic dipole in the second electromagnetic field map; determining a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole, and a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; and determining that there is the likelihood of the presence of the coronary artery disease in the individual if the first angle differs from the second angle by at least 100 degrees or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.

In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia. In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia with associated epicardial coronary artery disease. In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia without associated epicardial coronary artery disease. In some embodiments, the method further comprises shielding, using a shield, at least a portion of the individual from one or environmental magnetic fields. In some embodiments, the shield is configured to at least partially enclose a portion of a body of the individual which is associated with the magnetic field. In some embodiments, the portion of the body of the individual which is associated with the magnetic field is at least a portion of a chest of the individual. In some embodiments, the shield comprises two or more layers. In some embodiments, each of the two or more layers has a thickness of from 0.1 to 10 millimeters. In some embodiments, the shield comprises permalloy or mumetal. In some embodiments, the arm comprises a proximal segment and a distal segment, and wherein a second joint is positioned between the proximal segment and the distal segment and is configured so that the distal segment articulates relative to the proximal segment. In some embodiments, the array of one or more optically pumped magnetometers is movably coupled to the distal end of the arm so that the array of one or more optically pumped magnetometers moves relative to the arm with at least one degree of freedom. In some embodiments, the array of one or more optically pumped magnetometers comprises at least three optically pumped magnetometers. In some embodiments, the array of one or more optically pumped magnetometers is arranged to match a generalized contour of a portion of a body of the individual.

In some embodiments, the method further comprises filtering the first magnetic field and/or the second magnetic field. In some embodiments, the filtering comprises cancelling out a magnetic field sensed by a gradiometer. In some embodiments, the filtering comprises subtracting a frequency-based measurement from the first magnetic field and/or the second magnetic field.

In some embodiments, the method further comprises determining the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on (iii) a parameter selected from the group consisting of: dipole parameters, integrated MCD parameters, integrated ECD parameters, mean PCD parameters, isointegral parameters, field map correlation parameters, R_peak pegged dipole parameters, pseudo current arrow parameters, extrema circle parameters, phase space embedding parameters using delta coordinates, and phase space embedding parameters using time delay coordinates, or (iv) a visualization selected from the group consisting of: a STAG plot, a T_peak MFM plot, a field map animation, pseudo current density arrows, an MCD plot, and an ECD plot.

In some embodiments, the method further comprises determining the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on the parameter.

In some embodiments, the method further comprises determining the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on the visualization.

In some embodiments, the method further comprises determining the presence of the coronary artery disease in the individual based on a presence of at least one abnormality from among (i) whether the first angle differs from the second angle by at least 100 degrees, (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map, (iii) the parameter, and (iv) the visualization.

In some embodiments, the method further comprises determining the presence of the coronary artery disease in the individual based on a presence of at least two abnormalities from among (i) whether the first angle differs from the second angle by at least 100 degrees, (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map, (iii) the parameter, and (iv) the visualization.

Also described herein is a method for determining a likelihood of a presence of coronary artery disease in an individual, the method comprising: identifying a first negative electromagnetic dipole and a first positive electromagnetic dipole in a first electromagnetic field map associated with a heart of the individual at a first time; identifying a second negative electromagnetic dipole and second positive electromagnetic dipole in a second electromagnetic field map associated with the heart of the individual at a second time; determining a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole; determining a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; and determining that there is the likelihood of the presence of the coronary artery disease in the individual if the first angle differs from the second angle by at least 100 degrees or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.

In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia. In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia with associated epicardial coronary artery disease. In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia without associated epicardial coronary artery disease. In some embodiments, the method further comprises recording an electrocardiogram of the individual. In some embodiments, the first angle comprises a peak R-depolarization angle at the first time, wherein the first time is a time when an R-wave is recorded on the electrocardiogram. In some embodiments, the second angle comprises a peak T-repolarization angle at the second time, wherein the second time is a time when a T-wave is recorded on the electrocardiogram. In some embodiments, the third electromagnetic dipole is present in the second electromagnetic field map. In some embodiments, the coronary artery disease comprises an occlusion of the left anterior descending artery. In some embodiments, the first angle is determined by determining a first line that passes through both the first negative electromagnetic dipole and the first positive electromagnetic dipole, and determining the angle between the first line and a horizontal axis. In some embodiments, the second angle is determined by determining a second line that passes through both the second negative electromagnetic dipole and the second positive electromagnetic dipole, and determining the angle between the second line and a horizontal axis. In some embodiments, the likelihood of the presence of coronary artery disease in the individual is determined if the first angle differs from the second angle by 100 degrees to 170 degrees.

In some embodiments, the individual has either a normal electrocardiogram while experiencing chest pain or normal troponin level while experiencing chest pain. In some embodiments, the individual has had a positive stress test or abnormal echocardiogram findings. In some embodiments, the method further comprises performing a stress test if the first angle differs from the second angle or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map. In some embodiments, the method further comprises sensing, at the first time, a first electromagnetic field associated with the heart of the individual, and sensing, at the second time, a second electromagnetic field associated with the heart of the individual, wherein the first electromagnetic field map comprises a representation of the first electromagnetic field and the second electromagnetic field map comprises a representation of the second electromagnetic field. In some embodiments, the method further comprises determining a likelihood of a presence of a conduction abnormality in the heart of the individual if the first positive electromagnetic dipole and the second negative electromagnetic dipole have a same location or the first negative electromagnetic dipole and the second positive electromagnetic dipole have a same location. In some embodiments, the method further comprises treating the individual with a treatment for the coronary artery disease, responsive to determining the likelihood of the presence of the coronary artery disease (e.g., ischemia inducing pathophysiology) in the individual. In some embodiments, the treatment comprises a daily aspirin or ibuprofen regimen. In some embodiments, the treatment comprises a blood pressure lowering medication. In some embodiments, the treatment comprises a lipid lowering medication. In some embodiments, the treatment comprises a cardiac catheterization. In some embodiments, the treatment comprises a surgical intervention. In some embodiments, the method further comprises performing (a) to (e) by a computer.

In some embodiments, the method further comprises determining the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on (iii) a parameter selected from the group consisting of: dipole parameters, integrated MCD parameters, integrated ECD parameters, mean PCD parameters, isointegral parameters, field map correlation parameters, R_peak pegged dipole parameters, pseudo current arrow parameters, extrema circle parameters, phase space embedding parameters using delta coordinates, and phase space embedding parameters using time delay coordinates, or (iv) a visualization selected from the group consisting of: a STAG plot, a T_peak MFM plot, a field map animation, pseudo current density arrows, an MCD plot, and an ECD plot.

In some embodiments, the method further comprises determining the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on the parameter.

In some embodiments, the method further comprises determining the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on the visualization.

In some embodiments, the method further comprises determining the presence of the coronary artery disease in the individual based on a presence of at least one abnormality from among (i) whether the first angle differs from the second angle by at least 100 degrees, (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map, (iii) the parameter, and (iv) the visualization.

In some embodiments, the method further comprises determining the presence of the coronary artery disease in the individual based on a presence of at least two abnormalities from among (i) whether the first angle differs from the second angle by at least 100 degrees, (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map, (iii) the parameter, and (iv) the visualization.

Also described herein is a non-transitory computer-readable medium comprising machine executable code that, upon execution by one or more computer processors, implements a method for determining a likelihood of a presence of coronary artery disease in an individual, the method comprising: identifying a first negative electromagnetic dipole and a first positive electromagnetic dipole in a first electromagnetic field map associated with a heart of the individual at a first time; identifying a second negative electromagnetic dipole and second positive electromagnetic dipole in a second electromagnetic field map associated with the heart of the individual at a second time; determining a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole; determining a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; and determining that there is the likelihood of the coronary artery disease in the individual if the first angle differs from the second angle by at least 100 degrees or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.

In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia. In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia with associated epicardial coronary artery disease. In some embodiments, the coronary artery disease comprises cardiac myocyte ischemia without associated epicardial coronary artery disease.

Also described herein is a non-transitory computer-readable medium comprising machine-executable code that, upon execution by one or more computer processors, implements any of the methods above or elsewhere herein.

Also described herein is a system comprising one or more computer processors and computer memory coupled thereto. The computer memory comprises machine executable code that, upon execution by the one or more computer processors, implements any of the methods above or elsewhere herein.

Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. To the extent publications and patents or patent applications incorporated by reference contradict the disclosure contained in the specification, the specification is intended to supersede and/or take precedence over any such contradictory material.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent application file contains at least one drawing executed in color. Copies of this patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (also “figure” and “FIG.” herein), of which:

FIG. 1 shows one example of a sensor array, a shield, and a base unit.

FIG. 2 shows one example of a shield.

FIG. 3 shows one example of a shield and base unit.

FIG. 4 shows one example of a sensor array operatively coupled to a base unit.

FIG. 5 shows one example of a sensor array operatively coupled to an arm.

FIG. 6 shows one example of a sensor array operatively coupled to a base unit.

FIG. 7 shows one example of a sensor array operatively coupled to an arm of a base unit.

FIG. 8 shows a computer system that is programmed or otherwise configured to implement methods provided herein.

FIGS. 9A-9B show one example of a shield. The shield of FIG. 9A is positioned to show an open end and internal volume of the shield. The shield of FIG. 9B is positioned to show a closed end of the shield having a tapered or conical shape.

FIGS. 10A-10B show two different cross section views of a shield.

FIGS. 11A-11L show multiple views of one example of a shield.

FIGS. 12A-12B show multiple views of one example of external supports for a shield.

FIG. 13 shows one example of a hook.

FIGS. 14A-14B show multiple views of a mobile cart device.

FIGS. 15A-15C show multiple view of a mobile cart device.

FIG. 16 shows one example of a device in use in a magnetically shielded environment.

FIG. 17 shows an example of an individual sliding into a shield.

FIG. 18 shows an example of an embodiment of a shield comprising three layers of mumetal (three innermost layers) and one layer of aluminum alloy (outer layer).

FIG. 19 shows a plot of magnetic field measurements along the centerline of a shield.

FIG. 20 shows an example of a sensor array.

FIG. 21 shows an example of a 3D rendering of a sensor head cage mounted on a bed of a shield.

FIG. 22 shows an exemplary layout of one inner coil positioned in an embodiment of a shield.

FIG. 23 shows an exemplary layout of outer coils positioned in an embodiment of a shield.

FIG. 24 shows a typical equilibration function.

FIG. 25 shows an example method for assessing the presence of coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) in an individual.

FIGS. 26A-26B show an example of how methods and systems of the present disclosure may be used to analyze an electric current of an organ or tissue (e.g., a heart) of a subject and determine its associated magnetic field, including a depiction of Ampere’s Law (FIG. 26A) and an example of a magnetic field map generated from the electric current (FIG. 26B).

FIGS. 27A-27B show an example of how methods and systems of the present disclosure may be used to analyze an electric current of an organ or tissue (e.g., a heart) of a subject and determine its associated magnetic field, including a depiction of a peak R-depolarization angle 2702 (FIG. 27A) and a depiction of a peak T-repolarization angle 2704 (FIG. 27B), where an increased R-T angle gap is indicative of cardiac ischemia in the heart of the subject.

FIG. 28 shows how the heart generates electricity, including depolarization ion flow (non-energy dependent), in which (1) sodium slows its entering into the cell and potassium leaves the cell, and (2) large amounts of calcium enter the cell; repolarization ion flow (highly energy dependent), in which (3) calcium stops entering the cell and potassium leaves the cell, and (4) restored balance of the ions inside and outside of the cell (repolarized); and heart attack/ischemic cells, where the damaged cells are stuck at Zone 3 (depolarized) and can no longer contract.

FIG. 29 shows a “Wiggers Diagram” depicting the cardiac cycle, showing ventricular volume, ventricular pressure, aortic pressure, and atrial pressure, which shows that electrical generation precedes mechanical function of the heart.

FIG. 30 shows an example of assessment of patient intake using systems, devices, and methods of the present disclosure, including patients with stress testing, patients with negative MCG or positive MCG, patients with negative ST or positive ST, and patients with positive CA or negative CA.

FIG. 31 shows an example of a workflow for chest pain triage according to a clinical standard of care.

FIG. 32 shows an example of an improved workflow for chest pain triage according to systems, devices, and methods of the present disclosure.

FIG. 33 shows an example of output data obtained using methods and systems of the present disclosure, which is presented to the interpreting physician as a set of 36 superimposed waveforms of magnetic field intensity versus time for a single cardiac cycle. Each individual waveform represents the magnitude of the magnetic field normal to the chest wall measured at a distance of several inches above the torso. The system acquires data from 36 sensors arranged in a uniform 6 x 6 grid, so each dark circle shown in the map below represents a “true data point”, color coded to represent direction of magnetic field and its intensity. All information represented by the “sea of color” in the magnetic field map (MFM) external to the 36 grid points is interpolated using data from these grid points.

FIG. 34 shows an example of the output data obtained using methods and systems of the present disclosure after rendering in a wave form pattern, which mimics the traditional format of the voltage presentation of an electrocardiogram (ECG).

FIGS. 35A-35B show an example of R-peak and T-peak magnetic field maps, respectively, of a subject, which are interpreted to have a normal (e.g., non-ischemic) result, where the vector between the positive and negative electromagnetic dipoles during the R-peak and as compared to the T-peak are consistent.

FIGS. 36A-36B show an example of R-peak and T-peak magnetic field maps, respectively, of a subject, which are interpreted to have a normal (e.g., non-ischemic) result, where the vector between the positive and negative electromagnetic dipoles during the R-peak as compared to T-peak show a 180-degree flip.

FIGS. 37A-37B show an example of R-peak and T-peak magnetic field maps, respectively, of a subject, which are interpreted to have an abnormal (e.g., ischemic) result, where during the T-peak magnetic field map, multiple electromagnetic dipoles are present, which are completely surrounding the positive electromagnetic dipole.

FIGS. 38A-38B show an example of R-peak and T-peak magnetic field maps, respectively, of a subject, which are interpreted to have an abnormal (e.g., ischemic) result, where the vector between the positive and negative electromagnetic dipoles during the R-peak as compared to T-peak show a electromagnetic dipole movement of more than 100 degrees.

DETAILED DESCRIPTION

While various embodiments are shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It should be understood that various alternatives to the embodiments herein are employed.

As used herein, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Any reference to “or” herein is intended to encompass “and/or” unless otherwise stated.

As used herein, the term “about” may mean the referenced numeric indication plus or minus 15% of that referenced numeric indication.

Devices and Systems for Sensing a Magnetic Field

Described herein are devices and systems configured to sense a magnetic field associated with one or more tissues, one or more body portions, one or more organs, or an entire body of an individual. Non-limiting examples of organs and organ systems having a magnetic field that is sensed by the devices and systems described herein include the brain, heart, lungs, kidneys, liver, spleen, pancreas, esophagus, stomach, small bowel, and colon, the endocrine system, respiratory system, cardiovascular system, genitourinary system, nervous system, vascular system, lymphatic system, and digestive system. Non-limiting examples of tissue having a magnetic field that is sensed by the devices and systems described herein includes inflammatory tissue (including areas of inflamed tissue), blood vessels and blood flowing within blood vessels, lymphatic vessels and lymph flowing within lymphatic vessels, bone, and cartilage. Magnetic field data that is sensed is further processed in order to make determinations or assist a user (e.g. a healthcare provider) in making a determination about the one or more tissues, the one or more body portions, the one or more organs, or the entire body of the individual that is associated with that sensed magnetic field. For example, in some embodiments, a device as described herein is used to determine a prognosis of an individual, such as, for example, predicting a likelihood of an individual developing a disease or condition based on one or more magnetic fields that are sensed using the device. For example, in some embodiments, a device as described herein is used to determine a diagnosis, such as, for example, confirming a diagnosis or providing a diagnosis to an individual for a disease or condition based on one or more magnetic fields that are sensed using the device. For example, in some embodiments, a device as described herein is used to provide monitoring, such as monitoring a progression of a disease or condition in an individual, monitoring an effectiveness of a therapy provided to an individual, or a combination thereof based one or more magnetic fields that are sensed using the device. It should be understood that the devices and systems described herein are suitable for measuring a magnetic field associated with any type of tissue.

In some embodiments of the devices and systems described herein, sensed magnetic field data associated with a heart is used to generate a magnetocardiogram. In these embodiments of the devices and systems described herein, the devices and systems are utilized as a magnetocardiograph which is, for example, a passive, noninvasive bioelectric measurement tool intended to detect, record, and display magnetic fields that are naturally generated by electrical activity of a heart.

In some embodiments, a device or system as described herein is configured to measure one or more biomarkers in addition to a magnetic field. Non-limiting examples of biomarkers sensed in addition to a magnetic field using embodiments of the devices and systems described herein include a body temperature, a heart rate, blood pressure, an echocardiogram (ECG), a magnetic field, or any combination thereof.

In some embodiments, an individual, whose magnetic field is sensed, is in good health. In some embodiments, an individual, whose magnetic field is sensed, is an individual suspected of having a condition or disease. In some embodiments, an individual, whose magnetic field is sensed, is an individual having received a previous diagnosis of having a condition or disease.

In some embodiments, a condition or disease being identified in an individual is a cardiac condition or disease. In some embodiments, a cardiac condition or disease being identified in an individual comprises rheumatic heart disease, hypertensive heart disease, ischemic heart disease, cerebrovascular disease, inflammatory heart disease, valvular heart disease, an aneurysm, a stroke, atherosclerosis, arrhythmia, hypertension, angina, coronary artery disease, coronary heart disease, demand ischemia, a heart attack, cardiomyopathy, pericardial disease, congenital heart disease, heart failure, or any combination thereof.

A device as described herein, in some embodiments, comprises one or more sensors. In some embodiments, two or more sensors are arranged in a sensor array. In some embodiments, a device as described herein includes an electromagnetic shield, and some embodiments of the devices described herein do not include a shield.

Systems as described herein, in some embodiments, comprise any device as described herein and one or more local and/or remote processors.

Sensors and Sensor Arrays for Sensing a Magnetic Field

In some embodiments of the devices and systems described herein, a device comprises a sensor, such as an optically pumped magnetometer (OPM) as a measurement tool, which, in some embodiments, utilizes nonradioactive self-contained alkali metal cells coupled with a closed pumping laser and photodetector setup to measure minute magnetic fields. In some embodiments of the devices and systems described herein, the devices and systems utilize OPMs in an n x n array (or grid) or alternative geometric configuration to collect magnetic field data at n discrete locations over, for example, a portion of a body of an individual such as a chest area, which, in some embodiments, is digitized using pickup electronics.

OPMs are typically configured to utilize nonradioactive self-contained alkali metal cells coupled with a closed pumping laser and photodetector setup to measure minute magnetic fields. Compared to superconducting quantum interference devices (SQUIDs), which are typically also used to detect these biomagnetic fields, OPM sensors are significantly smaller and typically do not require the use of cryogenic cooling.

The Earth’s magnetic field is naturally present everywhere on Earth, and the amplitude is about 50 microtesla. OPM performance is enhanced in at least two exemplary ways in the presence of the Earth’s ambient magnetic field. In a first OPM enhancing technique, a reference value representing Earth’s magnetic field is used as part of a vector subtraction to isolate a signal of interest in an OPM. Another technique involves the use of a gradiometer for active noise cancellation for the OPM.

A sensor array configuration, as utilized in some embodiments of the devices and systems described herein, comprises a custom array configuration. In some embodiments, a sensor array configuration is customized to an individual’s anatomy. In some embodiments, a sensor array configuration is customized to a location on the individual which is measured, such as a chest location or a head location. In some embodiments, a sensor array configuration is customized to a measurement type that a device is programmed to acquire. In some embodiments, a sensor array configuration is customized to be operatively coupled with a shield and/or an arm. In some embodiments, a sensor array configuration is interchangeable with a different array configuration - a user may perform with interchange. An array configuration , in some embodiments, comprises an arc (such as a generally curved shape) having a depth and comprising a radius from about 20 cm to about 50 cm or from about 10 cm to about 60 cm. An array configuration, such as an arc configuration, in some embodiments, comprises one or more variable inter-magnetometer distances and variable sensor densities. An array configuration, in some embodiments, comprises a concave structure (such as a concave structure configured to wrap or form around a body region, such as a head or chest). One or more magnetometers is positioned on at least a portion of a surface of the concave structure. A concave array configuration, in some embodiments, comprises one or more variable inter-magnetometer distances and variable sensor density.

In some embodiments, a sensor array n x n sensors. In some embodiments, a sensor array is a 2D rectangular array, such as a 2 x 2 array or a 4 x 4 array. In some embodiments, a sensor array is a 2D non-rectangular array, such as a 2 x 1 array or a 4 x 1 array. In some embodiments, a sensor array is a circular array or a semicircular array, such as a 3D array of sensors positioned in an arc or concave structure. In some embodiments, a sensor array is a 2D array or a 3D array. In some embodiments, a sensor of a sensor array comprises x, y, and z coordinates. An array, in some embodiments, comprises a single sensor, such as n x n = 1 x 1. An array, in some embodiments, comprises two sensors, such as n x n = 2 x 1. An array, in some embodiments, comprises three sensors. An array, in some embodiments, comprises four sensors. An array, in some embodiments, comprises nine sensors. An array, in some embodiments, comprises sixteen sensors. An array, in some embodiments, comprises 25 sensors. An array, in some embodiments, comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 sensors or more. In some embodiments, a sensor array comprises 8 sensors. In some embodiments, a sensor array comprises 16 sensors. In some embodiments, a sensor array comprises a single sensor housed in a single housing. In some embodiments, a sensor array comprises a plurality of sensors housed in a single housing, such as a housing having multiple sensor configurations or changeable sensor configurations. In some embodiments, a sensor array comprises a plurality of sensors housed in a plurality of housings. In some embodiments, a sensor array comprises a plurality of sensors, each sensor housed in a separate housing. In some embodiments, a first sensor and second sensor of a sensor array is different. In some embodiments, a first sensor and a second sensor of a sensor array is the same. In some embodiments, each sensor of a sensor array is unique. In some embodiments, each sensor of a sensor array is identical. In some embodiments, a subset of sensors within a sensor array is unique. In some embodiments, a subset of sensors within a sensor array is identical. Spatial positioning of a sensor in a sensor array is adjustable, such as by a user or automated by a controller. In some embodiments, spatial positioning of a sensor in a sensor array is fixed. In some embodiments, a number of sensors in a sensor array is selected based on an application. In some embodiments, a number of sensors in a sensor array is selected based on a type of measurement or a location of a measurement. An array, in some embodiments, comprises a single channel array or a multi-channel array. In some embodiments, increasing a number of sensors of a sensor array increases a resolution of a measurement taken by the array. In some embodiments, a sensor array of sensors is densely packed, such as substantially adjacent or proximal one another. An array of sensors is sparsely spaced, such as having a spacing between one another. In some embodiments, a subset of sensors of a sensor array is densely packed. In some embodiments, a subset of sensors of a sensor array is sparsely spaced or densely spaced. In some embodiments, centerpoints of any two sensors of a densely packed subset of sensors is spaced less than about: 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.5, 0.1 centimeters (cm) apart. In some embodiments, centerpoints of densely packed sensors is spaced centerpoint to centerpoint from about 0.1 cm to about 2.0 cm or from about 0.1 cm to about 1.5 cm or from about 1.0 cm to about 2.0 cm. In some embodiments, centerpoints of any two sensors of a sparsely packed subset of sensors is spaced more than about: 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 8, 10 cm apart. In some embodiments, centerpoints of sparsely packed sensors is spaced centerpoint to centerpoint from about 1.5 cm to about 3 cm or from about 2 cm to about 5 cm or from about 2.5 cm to about 8 cm. In some embodiments, a center point is a central location of a sensor, such as a central axis. In some embodiments, a centerpoint of a circular sensor is a central point at which all other edge points are of equal distance.

In some embodiments, a densely packed array indicates intermagnetometer placement of less than 1.5 cm, while magnetometer placement of greater than about 1.5 cm constitutes a sparsely packed array.

In some embodiments, a housing is configured to house a sensor or a sensor array of sensors. In some embodiments, the housing is configured to accommodate a single configuration of sensor spacing within the housing. In some embodiments, the housing is configured to accommodate multiple configurations of sensor spacing within the housing. In some embodiments, the housing accommodates (i) adjusting sensor spacing, such as a dense spacing or a sparse spacing, or (ii) varying a number of sensors within the array. In some embodiments, a housing is a universal housing for a plurality of arrays and array configurations.

In some embodiments, a sensor is configured to sense a presence of or measure a parameter of a magnetic field. A sensor, in some embodiments, comprises a sensitivity to a magnetic field of about 10 femtotesla per root Hertz (fT/√Hz). A sensor, in some embodiments, comprises a sensitivity of from about 1 fT/√Hz to about 20 fT/√Hz. A sensor, in some embodiments, comprises a sensitivity of from about 5 fT/√Hz to about 15 fT/√Hz. A sensor, in some embodiments, comprises a sensitivity of from about 0.1 fT/√Hz to about 30 fT/√Hz. A sensor, in some embodiments, comprises a sensitivity of from about 0.5 fT/√Hz to about 12 fT/√Hz. A sensor, in some embodiments, comprises a sensitivity of from about 1 fT/√Hz to about 15 fT/√Hz. A sensor , in some embodiments, comprises a sensitivity of about: 0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 fT/√Hz.

In some embodiments, a sensor does not require a cooling element, such as cryogenic cooling, to collect a measurement. In some embodiments, a sensor collects a measurement over a temperature range of from about 30° F. (F) to about 110° F. In some embodiments, a sensor collects a measurement over a temperature range of from about 50° F. to about 110° F. In some embodiments, a sensor collects a measurement over a time period of from about 1 second to about 5 hours without a need for a cooling element. In some embodiments, a sensor collects a measurement over a time period of from about 1 second to about 1 hour without a need for a cooling element. In some embodiments, a sensor collect a measurement over a time period of from about 1 second to about 30 minutes without a need for a cooling element.

A noise source, in some embodiments, comprises a magnetic field strength. In some embodiments, a strength of a magnetic field of a noise source is measured in units of Tesla (T). Noise, such as ambient noise, in some embodiments, comprises a magnetic field strength of less than about 100 nanotesla (nT). Noise, in some embodiments, comprises a magnetic field strength of less than about 1000 nT. Noise, in some embodiments, comprises a magnetic field strength of less than about 500 nT. Noise, in some embodiments, comprises a magnetic field strength of less that about 200 nT. Noise, in some embodiments, comprises a magnetic field strength of less than about 120 nT. Noise, in some embodiments, comprises a magnetic field strength of less than about 80nT. A noise source, such as a magnetic field of the Earth, , in some embodiments, comprises a magnetic field strength of about 50 microtesla (mT). Noise, in some embodiments, comprises a magnetic field strength of from about 40mT to about 60mT. Noise, in some embodiments, comprises a magnetic field strength of from about 10mT to about 100mT. Noise, in some embodiments, comprises an amplitude component, a frequency component, or a combination thereof, and, in some embodiments, comprises both sources that is direct current (DC), alternating current (AC), or a combination of the two.

Electromagnetic Shield

Some embodiments of the devices and systems as described herein are configured to provide an electromagnetic shield to reduce or eliminate the ambient magnetic field of the Earth. A shield as described herein, in some embodiments, comprises a metal alloy (e.g. permalloy or mumetal), which when annealed in a hydrogen furnace provides exceptionally high magnetic permeability, thereby isolating regions protected by the shield (e.g. within a shield shaped as a chamber) from the Earth’s magnetic field.

A chamber or shield as described herein minimizes interior magnetic fields, and, in some embodiments, is constructed with one closed end and one open end. The closed end, in some embodiments, takes the form of a flat, conical, or domed endcap.

In some embodiments, utilization of a shield with sensor, such as a sensor array provides a reduction of noise such that the sensor collects a measurement that is substantially free of a noise or collects a measurement in which a noise is significantly reduced. A noise, in some embodiments, comprises a noise from a noise source. In some embodiments, a noise source includes a high frequency noise, such as greater than about 20 Hz, a middle frequency noise, such as from about 1 Hz to about 20 Hz, a low frequency noise such as from about 0.1 Hz to about 1 Hz, or any combination thereof. In some embodiments, a noise source includes any structure comprising metal. In some embodiments, a structure comprising metal includes a metal implant such as a pacemaker, a defibrillator, an orthopedic implant, a dental implant, or others. In some embodiments, a structure comprising metal includes a metal tool, a metal door, a metal chair, or others. In some embodiments, a noise source includes operation of a device such as a fan, an air conditioner, a clinical apparatus, or vibrations of a building. In some embodiments, a noise source includes operation of a power supply or an electronic device such as a computer comprising a monitor or graphical user interface.

A shield or portion thereof, in some embodiments, comprises a single layer of material. A shield or portion thereof, in some embodiments, comprises a plurality of layers of a material. A shield or portion thereof, in some embodiments, comprises a plurality of layers, wherein at least two of a plurality of layers comprise different materials. A shield or portion thereof, in some embodiments, comprises 2 layers. A shield or portion thereof, in some embodiments, comprises 3 layers. A shield or portion thereof, in some embodiments, comprises 4 layers. A shield or portion thereof, in some embodiments, comprises 5 layers. A shield or portion thereof, in some embodiments, comprises 6 layers.

A layer of a shield or portion thereof, in some embodiments, comprises a thickness from about 0.1 to about 10 millimeters. In some embodiments, a layer of a shield has a thickness from about 0.5 to about 5 millimeters. In some embodiments, a layer of a shield has a thickness from about 0.1 to about 2 millimeters. In some embodiments, a layer of a shield has a thickness from about 0.8 to about 5 millimeters. A thickness is substantially the same along a length or a circumference of a shield. In some embodiments, a thickness of a layer of a shield varies along a length or circumference of a shield.

In some embodiments, a shield comprises a plurality of layers. In some embodiments, a space is present between at least two layers of the plurality of layers. In some embodiments, a space is present between each layer of the plurality of layers. In some embodiments, a space is present between a subset of layers of the plurality of layers. In some embodiments, a first layer of a shield is configured to be adjacent a second layer of a shield. In some embodiments, a first layer of a shield is configured to be attached or bonded to a second layer of a shield. In some embodiments, a first layer of a shield is configured to be positioned from about 0.1 inches to about 5 inches from a second layer. In some embodiments, a first layer of a shield is configured to be positioned from about 1 inch to about 3 inches from a second layer. In some embodiments, a first layer of a shield is configured to be positioned from about 1 inch to about 20 inches from a second layer. In some embodiments, a first layer of a shield is configured to be positioned from about 1 inch to about 10 inches from a second layer.

In some embodiments, a length of a shield, such as an internal length or an external length, is about 2x an internal diameter of a shield. In some embodiments, a length of a shield is from about 0.5x to about 3x an internal diameter of a shield. In some embodiments, a length of a shield is from about 1x to about 3x an internal diameter of a shield. In some embodiments, a length of a shield is from about 1.5x to about 3x an internal diameter of a shield.

In some embodiments, a length of a shield is configured to accommodate at least a portion of an individual. In some embodiments, a length of a shield is configured to accommodate an individual. In some embodiments, a diameter of a shield, such as an internal diameter, is configured to accommodate at least a portion of an individual. In some embodiments, a diameter of a shield, such as an internal diameter, is configured to accommodate an individual. In some embodiments, an individual is a human subject. In some embodiments, a human subject is an adult subject, a pediatric subject, or a neonatal subject.

In some embodiments, a length of a shield is from about 40 inches to about 100 inches. In some embodiments, a length of a shield is from about 50 inches to about 90 inches. In some embodiments, a length of a shield is from about 40 inches to about 150 inches. In some embodiments, a length of a shield is from about 60 inches to about 90 inches.

In some embodiments, a diameter of a shield is from about 40 inches to about 60 inches. In some embodiments, a diameter of a shield is from about 45 inches to about 55 inches. In some embodiments, a diameter of a shield is from about 50 inches to about 70 inches.

In some embodiments, a shield or portion thereof is configured in a substantially cylindrical shape. In some embodiments, a shield or portion thereof is configured in a substantially conical shape. In some embodiments, a shield comprises a first end and a second end. In some embodiments, a first end of a shield comprises a substantially cylindrical shape and a second end of a shield comprises a conical shape. In some embodiments, a shield is configured with a first end having a cylindrical shape that is tapered, such as gradually tapered, to a second end having a conical shape.

In some embodiments, a shield comprises an internal volume configured for placing an individual, a sensor, or a combination thereof within the internal volume. When an individual is placed into an internal volume of a shield, reducing an excess of internal volume is desirable. For example, providing a shield having a tapered end or a conical end reduces an excess of internal volume, improves spatial homogeneity of a measurement taking by a sensor, reduces noise, or any combination thereof.

In some embodiments, a measurement collected from a sensor is collected from inside an internal volume of a shield. In some embodiments, a measurement is collected in the absence of an individual. In some embodiments, a measurement is collected in the presence of an individual. In some embodiments, a shield comprises a portion of an internal volume having a greater spatial homogeneity or greater amount of noise reduction as compared with a different portion. For example, a tapered end or a conical shaped end of an internal volume has greater spatial homogeneity of a measurement, a noise reduction, or both as compared to a cylindrical shaped end. In some embodiments, an individual is positioned within an internal volume of a shield such that an area of the subject desired to be measured by the sensor is positioned within a portion of the internal volume having greater spatial homogeneity of a measurement, a reduction in noise, or both.

In some embodiments, altering a length of a shield, altering a diameter of a shield, altering a shape of a shield (such as a tapering) alters noise reduction and quality of a measurement within an internal volume of a shield. Each is independently altered or collectively altered to optimize noise reduction or improve quality of a measurement taken by a sensor.

In some embodiments, a shield comprises a coil, such as a Helmholtz coil. In some embodiments, a coil generates a current within the coil. In some embodiments, addition of a coil to a shield improves a quality of a measurement (such as a spatial homogeneity of a measurement), reduces a noise, or a combination thereof. In some embodiments, a shield comprises a plurality of coils. A shield, in some embodiments, comprises a single coil. A shield, in some embodiments, comprises two coils. A shield, in some embodiments, comprises three coils. A shield, in some embodiments, comprises from 1 to 3 coils. In some embodiments, a coil is positioned within a portion of a shield. In some embodiments, a coil is positioned within a portion of a shield that a measurement occurs. In some embodiments, a position of a coil is adjustable, such as by a controller or by a user. In some embodiments, a position of a coil is adjusted for each measurement of a sensor. In some embodiments, a position of a coil is pre-programed accordingly to a type of measurement of a sensor. In some embodiments, a position of a coil is adjustable with an accuracy of from about 0.1 inches to about 5 inches. In some embodiments, a coil provides feedback to a user or to a controller that a desired positioned is achieved by the coil. In some embodiments, a feedback from a coil to a user or to a controller occurs prior to a measurement, during a measurement, or after a measurement of a sensor. In some embodiments, a feedback from a coil confirms that a desired position (such as a position corresponding to a position of an individual desired to be measured) is reached.

In some embodiments, a shield is modular. In some embodiments, a shield or portion thereof is disposable. In some embodiments, a shield is configured to accept at least a portion of an individual, at least a portion of a sensor array, or a combination thereof. A portion of an individual, in some embodiments, comprises a head, an arm, or a leg that is placed into an inner volume of a shield. A portion of an individual, in some embodiments, comprises an individual from a mid-section to a head or from a mid-section to a foot. In some embodiments, a shield is not modular. In some embodiments, a shield is configured to interact with one or more modular units. For example, a modular unit, such as base unit, is modular and configured to modulate in relation to a shield that is stationary or non-modular.

In some embodiments, a shield or portion thereof is configured for subject comfort. In some embodiments, a shield or portion thereof is configured with lighting, such as an internal volume of a shield, in some embodiments, comprises a lighting source. In some embodiments, a shield or portion thereof is configured with venting, such as one or more ports or openings, such as one or more openings positioned on an internal surface of a shield.

A shield, in some embodiments, comprises a single material. A shield, in some embodiments, comprises more than one material. A shield or a portion thereof, in some embodiments, comprises a metal, a metal alloy, or a combination thereof. A shield or a portion thereof, in some embodiments, comprises a permalloy or a mumetal. A shield or a portion thereof, in some embodiments, comprises aluminum, copper, gold, iron, nickel, platinum, silver, tin, zinc, or any combination thereof. A shield or a portion thereof, in some embodiments, comprises brass, bronze, steel, chromoly, stainless steel, titanium, or any combination thereof.

A shield or a portion thereof, in some embodiments, comprises nickel, iron, or a combination thereof. In some embodiments, a shield or portion thereof comprises from about 70% to about 90% by weight of nickel. In some embodiments, a shield or portion thereof comprises from about 75% to about 85% by weight of nickel. In some embodiments, a shield or portion thereof comprises from about 10% to about 30% by weight of iron. In some embodiments, a shield or portion thereof comprises from about 15% to about 25% by weight of iron. In some embodiments, a shield or portion thereof comprises from about 70% to about 90% by weight of nickel and from about 10% to about 30% by weight of iron. In some embodiments, a shield or portion thereof comprises from about 40% to about 60% by weight nickel and about 50% to about 60% by weight of iron. In some embodiments, a shield or portion thereof comprising a permalloy or a mumetal also comprises one or more additional elements such as molybdenum.

A shield or portion thereof, in some embodiments, comprises a material having a high permeability. For example, a material, in some embodiments, comprises a relative permeability of from about 50,000 to about 900,000 as compared to for example steel having a relative permeability of from about 4,000 to about 12,000. A material, in some embodiments, comprises a relative permeability of from about 75,000 to about 125,000. A material, in some embodiments, comprises a relative permeability of from about 400,000 to about 800,000. A material, in some embodiments, comprises a relative permeability of greater than about 50,000. A material, in some embodiments, comprises a relative permeability of greater than about 75,000. A material, in some embodiments, comprises a relative permeability of greater than about 100,000. A material, in some embodiments, comprises a relative permeability of greater than about 200,000. A material, in some embodiments, comprises a relative permeability of greater than about 300,000. A material, in some embodiments, comprises a relative permeability of greater than about 400,000. A material, in some embodiments, comprises a relative permeability of greater than about 500,000. A material, in some embodiments, comprises a relative permeability of greater than about 600,000. A material, in some embodiments, comprises a relative permeability from about 80,000 to about 900,000. A material, in some embodiments, comprises a relative permeability from about 400,000 to about 800,000.

In some embodiments, a shield is monolith in form. In some embodiments, a shield is formed of a plurality of subcomponents configured together. In some embodiments, a shield is 3D printed. A shield, in some embodiments, comprises a material formed in a hydrogen furnace, such as a shield comprising one or more materials annealed in a hydrogen furnace.

Described herein are devices and systems configured to sense a magnetic field associated with, for example, a tissue, a body part, or an organ of an individual. In some embodiments of the devices and systems described herein, a device for sensing a magnetic field comprises a mobile base unit and one or more magnetic field sensors. In some embodiments of the devices and systems described herein, a device for sensing a magnetic field comprises a mobile base unit, one or more magnetic field sensors, and a shield for shielding ambient electromagnetic noise.

In some embodiments of the devices and systems described herein, a device for sensing a magnetic field comprises a mobile base unit that is configured for portability. In some embodiments, a mobile base unit includes wheels or a track upon which the mobile base unit is moved on a surface. In some embodiments, a mobile base unit is hand-held. A mobile base unit is configured, in some embodiments, to comprise a housing containing electronic components.

In some embodiments of the devices and systems described herein, a device for sensing a magnetic field comprises one or more magnetic field sensors such as, for example, one or more OPMs.

In some embodiments of the devices and systems described herein, a device for sensing a magnetic field comprises one or more coupling mechanisms for receiving and coupling with one or more sensors. In some embodiments of the systems and devices described herein, a device for sensing a magnetic field coupler comprises one or more arms or extensions that connect with the mobile base unit. In some embodiments of the devices and systems described herein, a device for sensing a magnetic field includes one or more extensions or arms configured to move, rotate, and/or articulate so as to position one or more sensors for sensing a magnetic field within proximity to an individual whose magnetic field is to be sensed.

In some embodiments, a device or system as described herein comprises a mechanical housing that comprises one or more nonferrous materials, such as, for example, an aluminum alloy, a rubber, a plastic, a wood or any combination thereof to minimize an amount of interference seen in a biomagnetic signal from a device or system itself.

Exemplary Embodiments

FIG. 1 shows an exemplary embodiment of a device for sensing a magnetic field 100 as described herein comprising a shield 107. A device for sensing a magnetic field 100 comprises a shield 107 and one or more sensors 106 (such as an optically pumped magnetometer). In some embodiments, two or more sensors 106 are arranged in an array.

A shield 107 comprises an open end 109 and a closed end 108. In some embodiments, the open end 109 is positioned adjacent to the closed end 108. In some embodiments, the open end 109 is positioned opposite to the closed end 108. A shield 107, in some embodiments, comprises one or more openings. One or more openings of the shield 107 are configured to receive at least a portion of a base unit 101, at least a portion of an individual 114, at least a portion of the one or more sensors 106, or any combination thereof.

For example, a shield 107 comprises an opening, such as a recess opening 113 configured to receive a portion of a base unit 101. A shield 107, in some embodiments, comprises an opening 115 configured to receive at least a portion of a base unit 101, at least a portion of an individual 114, at least a portion of one or more sensors 106, or any combination thereof. A shield 107 comprises an inner surface 110. In some embodiments, an inner surface 110, which, in some embodiments, comprises a coating. In some embodiments, an inner surface 110 of a shield 107 defines an inner volume of a shield. An inner volume of a shield 107 is a volume into which a portion of an individual 114, a portion of a sensor, a portion of a base unit 101, or any combination thereof is received. A shield 107 comprises a shield portion 116 configured to store a component of a device for sensing a magnetic field, such as an electronic driver. A shield portion 116, in some embodiments, comprises a drawer, a shelf, a cabinet, a compartment, or a section of a shield 107. A shield portion 116, in some embodiments, is positioned on a side portion of a shield. A shield portion 116, in some embodiments, is positioned on a bottom of a shield 107.

In some embodiments, a device for sensing a magnetic field 100 as described herein comprises a base unit 101. In the exemplary embodiment shown in FIG. 1 , a base unit 101 comprises a bed or gurney on which an individual 114 lies.

In some embodiments, a device for sensing a magnetic field 100 as described herein is operatively coupled with a base unit 101. In some embodiments, a shield 107 is configured to receive a portion of a base unit 101. For example, a recess opening of a shield 107 is, in some embodiments, configured to receive at least a portion of a base unit 101, as shown in FIG. 1 . In some embodiments, a base unit 101 is directly attachable to one or more sensors 106.

A base unit 101, in some embodiments, is configured as a stationary base unit 101. A base unit 101, in some embodiments, is configured as a mobile base unit 101. In some embodiments, a shield 107 is movable relative to a base unit 101. In some embodiments, a base unit 101 is movable relative to a shield 107. In some embodiments, a base unit 101 and a shield 107 are movable relative to one another.

In the exemplary embodiment shown in FIG. 1 , a base unit 101 is configured as a movable base unit 101, A movable base unit 101, in some embodiments, is configured to move in one or more degrees of freedom (e.g. relative to a shield 107). In some embodiments, a movable base unit 101 is configured to move along an x axis, a y axis, a z axis, or any combination thereof. A movable base unit 101, in some embodiments, comprises one or more rotating elements such as a wheel (113 a, 113 b), a roller, a conveyor belt, or any combination thereof configured to provide movement of a base unit 101 or a portion thereof. In some embodiments, a base unit 101 comprises one rotating element. In some embodiments, a base unit 101 comprises two rotating elements. In some embodiments, a base unit 101 comprises three rotating elements. In some embodiments, a base unit 101 comprises four rotating elements. In some embodiments, a base unit 101 comprises more than four rotating elements. In some embodiments, a rotating element is positioned at one or both ends of a base unit 101. In some embodiments, a base unit 101 comprises a non-rotating element configured to be received into a track or channel such that the base unit 101 is movable along the track or channel. In some embodiments, the track or channel is positioned adjacent thereto a shield 107, such that the base unit 101 is movable towards, away, or both from the shield along the track or channel.

A base unit 101, in some embodiments, comprises one or more pivots (102 a, 102 b). In some embodiments, a base unit 101 comprises one pivot. In some embodiments, a base unit 101 comprises two pivots. In some embodiments, a base unit 101 comprises more than two pivots. A pivot 102 a, 102 b, in some embodiments, is configured to permit movement of a base unit 101 such as by accommodating an individual being positioned onto a base unit 101. A pivot 102 a, 102 b, in some embodiments, is configured to permit movement of a base unit 101 such as to position the base unit 101 within an inner volume of a shield 107. A pivot 102 a, 102 b, in some embodiments, is configured to provide movement to the base unit 101, providing one or more degrees of freedom.

In some embodiments, one or more sensors 106 are operatively coupled to an arm 103. An arm 103, in some embodiments, is a movable arm 103. In some embodiments, the device has an extensible arm 103, at the end of which, a sensor array 106 is housed. In some embodiments, any type of OPM is used as one or more of the one or more sensors 106. In some embodiments, an arm 103 is movable in at least one degree of freedom. An arm 103, in some embodiments, comprises a joint 104 configured to provide movement to the arm 103. In some embodiments, an arm 103 comprises more than one joint 104. In some embodiments, an arm 103 comprises two joints 104. An arm 103, in some embodiments, is operatively coupled one or more sensors 106 and to a base unit 101, such as shown in FIG. 1 . An arm 103, as shown in FIG. 1 , is operatively coupled to a base unit 101 by a beam 105.

In some embodiments, a device for sensing a magnetic field 100 as described herein comprises a computer processor 112, as shown in FIG. 1 . A computer processor 112, in some embodiments, comprises a graphical user interface. A computer processor 112, in some embodiments, comprises a touchscreen.

A device for sensing a magnetic field 100, as shown in FIG. 1 , comprises a stand 111 configured to, for example, receive a computer processor 112. A stand 111, in some embodiments, is positioned adjacent to a shield 107 or a base unit 101 of a device for sensing a magnetic field 100. A stand 111, in some embodiments, is integral to or attachable to a shield 107 or a base unit 101 of a device for sensing a magnetic field 100.

In some embodiments of the device 100 shown in FIG. 1 , the device is essentially stationary. It should be understood that other embodiments of the device 100 (and systems) described herein are configured to be mobile.

In some embodiments, the device 100 includes a compartment 116 or a tabletop to house electronics, a computer interface, and a power supply, and in others it includes a separate unit to house these components, connected to the first component by wiring. In some embodiments, the device 100 requires a power supply via an electrical outlet. In some embodiments, standard operating procedure include extending a device’s arm 103 and lowering a base of a sensor unit 106 to a position, such as a position that is within 2 centimeters adjacent a skin surface of an individual (such as an individual’s 114 chest, head, or other region of interest). The device 100, in some embodiments, is calibrated using a software application that is provided with the device or provided separately. In some embodiments, a biomagnetic signal of interest is displayed and recorded for immediate or later analysis.

Operation of a device (or system) 100 as described herein, in some embodiments, is controlled using either a software User Interface (UI) or manual UI or a combination UI including software and manual elements. In some embodiments, a UI is installed on site, on a provided accessory computer. The use of the device is prescribed by a medical professional such as a physician to determine more information regarding an individual’s condition. Within the UI, User preferences and acquisition parameters are chosen, including a sampling rate and an axis operation of the device or system. From the software user interface, magnetic field signals from an individual, such as signals corresponding to an individual’s heart, is displayed and saved to a file. In some embodiments, the device or system is configured to measure cardiac electrical activity, creating waveforms similar to electrocardiograph recordings which may demonstrate points of interest in a cardiac cycle.

One or more sensors 106 are arranged in an array wherein one or more optically pumped magnetometers outputs one or more waveforms. An array, in some embodiments, outputs one waveform per sensor of the array. In some embodiments, individual waveforms of individual sensors are combined into a single waveform. An array, in some embodiments, outputs a single waveform which comprises a combination of waveforms from each sensor of the array. In some embodiments, magnetic field data is visualized as a series of 2D images made from interpolated magnetic field values between sensors. In some embodiments, an array comprises at least one OPM and at least one other type of magnetomitor. In some embodiments, an array comprises only OPMs.

The shield 107, in some embodiments, is housed in a shrouded structure, and the total device length, in some embodiments, is at minimum of about 2.25 meters (m) in length, with a bore opening (or an internal opening diameter) of about 0.8 m.

In some embodiments, in order to insert an individual into a shield 107, a base unit 101 such as a bed platform is used upon which the subject is positioned. During device use, a flexible jointed arm 103 with x-y-z translational movement is configured to occupy any point within a semicircle defined by total arm length at extension is used to position an array of n-optically pumped magnetometers in a wide range of geometries on or proximally above a portion of an individual (such as an individual’s 114 chest, head, or other organ) using a set standard operating procedure based on an organ of interest, a condition or disease of interest, or a combination thereof. In some embodiments, after this point, the sensor array is turned on and at least a portion of the subject, at least a portion of the base unit 101 (e.g. bed platform), or a combination thereof is slid into the shield 107. Using a provided computer application, fast calibration of the sensors occurs, and then the magnetic field of the organ of interest is displayed, and recorded, or a combination thereof for immediate or later analysis. In some embodiments, electronic drivers for the sensors are housed either underneath the shield 107 portion of the device 100, or are housed in an adjacent cart with computer control.

The system, in some embodiments, comprises a touch screen computer interface (such as a graphical user interface) housed on a side of the device itself, or on said adjacent cart.

As shown in FIG. 2 , a shield, in some embodiments, comprises a shield frame 200. A shield frame 200, in some embodiments, provides a macrostructure or shape for the shield. In some embodiments, a shield frame 200 is positioned at an inner surface or an outer surface of the shield. In some embodiments, a shield frame 200 is configured to receive one or more portions of a base unit. In some embodiments, a shield frame 200 comprises an open end 201 and a closed end 203. In some embodiments, an opening 202 is positioned on the open end 201, such as an opening configured to receive a portion of a base unit. In some embodiments, an opening, such as a recess opening 204, is positioned on the open end 201 or a closed end 203, and is configured to receive a portion of a base unit. In some embodiments, a shield frame 200 comprises individual elements operatively connected to form the shield frame 200 or the shield frame 200, in some embodiments, comprises a single monolith frame or 3D printed frame. In some embodiments, a shield frame 200 comprises one or more layers.

As shown in FIG. 3 , an exemplary embodiment of a device or system 300 as described herein comprises a shield 301. The shield 301 comprises a closed end 302 and an open end 303. In some embodiments, an open end 303 of a shield 301 is positioned opposite a closed end 302 of the shield 301. In some embodiments, an open end 303 of a shield 301 is positioned adjacent to a closed end 302 of the shield 301. In some embodiments, an open end 303 is configured to position a sensor, an individual 305, a base unit 306 (such as a movable base unit), or any combination thereof within an inner volume of the shield 301. In some embodiments, a shield 301 comprises an inner surface 304. In some embodiments, an inner surface 304 of a shield 301 spatially defines an inner volume of the shield 301. In some embodiments, an inner surface 304 is configured to interface with an individual 305. In some embodiments, an inner surface 304 comprises venting or lighting to accommodate an individual 305. In some embodiments, a base unit 306 comprises one or more pivots, such that one or more portions of a base unit 306 is adjustable. For example, a base unit 306, in some embodiments, comprises a first pivot 307 and a second pivot 308. In some embodiments, a pivot is configured to adjust a position of a base unit 306 relative to a shield 301. In some embodiments, a pivot is configured to adjust a position of a base unit 306 relative in an inner volume of a shield 301. In some embodiments, a base unit 306 comprises 1, 2, 3, 4, 5, 6, 7, 8 or more pivots. In some embodiments, a pivot provides a movement in one or more degrees of freedom. In some embodiments, a pivot provides a bending motion. In some embodiments, a pivot provides a rotational motion. In some embodiments, a pivot provides an extending motion. In some embodiments, a base unit 306 comprises a base 309. In some embodiments, a base 309 is configured to support a portion of the base unit 306 that holds an individual 305, a sensor, a sensor array or a combination thereof. In some embodiments, a base 309 is configured to move into an opening 310 of a shield 301, such that a portion of the base unit 306 that holds an individual 305, an array, or a combination thereof is moved into and out of an internal volume of the shield 301. In some embodiments, an internal volume of a shield 301 comprises a structure 311, such as a track or channel or rod or protrusion that is configured to accept a portion of the base unit 306 (such as a portion associated with an individual 305, an sensor or both) as the portion is moved into and out of the internal volume of the shield 301.

As shown in FIG. 4 , an exemplary device or system 400 as described herein comprises a base unit 412 (such as a mobile base unit 412) and one or more sensors that in some embodiments comprise an array of sensors 401 (such as an optically pumped magnetometer).

In some embodiments, a device 400 comprises a structure 402, such as a handle, a beam, or rod, or protrusion that is configured to allow a user to adjust a position of the array 401.

In some embodiments a device 400 comprises one or more pivots (such as 403 or 408). In some embodiments, a pivot adjusts a position of a base unit 412 or a subcomponent thereof, a position of an array 401, or a combination thereof. In some embodiments, a pivot (403 or 408) is adjusted manually, automatically, or a combination thereof. In some embodiments, a pivot (403 or 408) is adjusted by a user, by a controller, or a combination thereof. In some embodiments, a pivot (403 or 408) is configured to provide movement in one or more degrees of freedom. In some embodiments, a pivot (403 or 408) provides a bending motion. In some embodiments, a pivot (403 or 408) provides an extending motion. In some embodiments, a pivot (403 or 408) provides a rotational motion.

In some embodiments, a base unit 412 comprises one or more compartments (such as 410 or 411). In some embodiments, a base unit 412 comprises a single compartment. In some embodiments, a base unit 412 comprises two compartments. In some embodiments, a base unit 412 comprises a plurality of compartments. In some embodiments, a base unit 412 comprises three compartments. In some embodiments, a first compartment and a second compartment are different. In some embodiments, a first compartment and a second compartment are the same. In some embodiments, a first compartment is larger in size than a second compartment. In some embodiments, a first compartment is positioned adjacent to a second compartment. In some embodiments, a first compartment is positioned above a second compartment. In some embodiments, a first compartment is positioned within a second compartment. In some embodiments, a compartment is configured to house one or more components. For example, a compartment is configured to house a power source, such that a base unit 412 is not restricted to remain proximal to a wall outlet or external power source. In some embodiments, a compartment is configured to house a computer including an operating system, a database, a monitor, a graphical user interface, or any combination thereof. In some embodiments, a compartment is configured to house one or more sensors or a housing for a sensor.

In some embodiments, a base unit 412 comprises one or more compartments (such as 409 or 410). In some embodiments, a base unit 412 comprises a single compartment. In some embodiments, a base unit 412 comprises two compartments. In some embodiments, a base unit 412 comprises a plurality of compartments. In some embodiments, a base unit 412 comprises three compartments. In some embodiments, a first compartment and a second compartment are different. In some embodiments, a first compartment and a second compartment are the same. In some embodiments, a first compartment is larger in size than a second compartment. In some embodiments, a first compartment is positioned adjacent to a second compartment. In some embodiments, a first compartment is positioned above a second compartment. In some embodiments, a first compartment is positioned within a second compartment. In some embodiments, a compartment is configured to house one or more components. For example, a compartment is configured to house a power source, such that a base unit 412 is not restricted to remain proximal to a wall outlet or external power source. In some embodiments, a compartment is configured to house a computer including an operating system, a database, a monitor, a graphical user interface, or any combination thereof. In some embodiments, a compartment is configured to house one or more sensors or a housing for a sensor.

In some embodiments, a base unit 412 comprises a surface 409, such as a flat surface. The surface 409 is configured to hold a computer or other component of the system. In some embodiments, a base unit 412 comprises one or more rotating elements (such as 414 a or 414 b). In some embodiments, a rotating element comprises a wheel (414 a, 414 b), a roller, a conveyor belt, or any combination thereof configured to provide movement of a base unit 412. A base unit 412, in some embodiments, comprises an arm 413. In some embodiments, one end of an arm 413 is configured to associate with the array 401 of sensors. In some embodiments, a second end of an arm 413 is configured to associate with the base unit 412, at for example a compartment 410 or 411 or a surface 409. In some embodiments, an arm 413 is adjustable. For example, an arm 413 is extendible in length, such as a first portion 405 of an arm 413 that extends from a second portion 407 of an arm 413. In some embodiments, a first 405 or second 407 portion of an arm 413 comprises a lock element (such as a knob or protrusion or pin-in-groove) for securing the arm 413 or the first 405 or second 407 portion of the arm 413 in an extended, flexed, or collapsed position.

In some embodiments, a pivot 408 is positioned at a first end 405 of an arm 413, at a second end 407 of an arm 413 (as shown in FIG. 4 ), or a combination thereof. In some embodiments, a pivot 403 is positioned at an end of an arm 413 that is adjacent an array 401. In some embodiments, a pivot 408 is positioned at an end of an arm 413 that is adjacent a compartment 410 or 411 or a surface 409. In some embodiments, a base unit 412 comprises wiring 404, such as one or more wires. Wiring 404 is configured to associate with one or more sensors of an array 401, one or more power sources of the base unit 412, one or more computers of the base unit 412, or any combination thereof. The base unit 412, in some embodiments, comprises a wire securing element 406 (such as a tie or latch or hook) to secure one or more wires of the base unit 412. In some embodiments, a wire securing element 406 is positioned on an arm 413 of the base unit 412. In some embodiments, a wire securing element 406 is positioned in a compartment of the base unit 412. In some embodiments, a wire securing element 406 is positioned proximal an array 401, proximal an extension point of an arm 413, proximal a pivot (403 or 408), or any combination thereof.

In some embodiments, a device 400 is combined with a shield (not shown) such as, for example, a disposable shield or a modular shield. In some embodiments, a shield is separate from a base unit 412. In some embodiments, a shield is associated with a base unit 412, such as attached to a base unit 412 at a position that is proximal the array 401.

In some embodiments, a shield is integral to the device 400. In some embodiments, a shield, an array 401, an arm 413, or any combination thereof is operatively connected (such as by wiring or wirelessly) to a controller or computer system.

As shown in FIG. 5 , in some embodiments of the devices and systems described herein, an arm 500 of a mobile cart device comprises an articulating and/or extending mechanism 501. As shown in FIG. 5 , in some embodiments an extending mechanism 501 comprises a telescoping housing for a portion of arm 500 to telescope in and out of. In some embodiments, an articulating mechanism 501 comprises a joint.

An arm 500, in some embodiments, comprises one or more holders 502, such as a holder for securing a wiring component 503 to a position on the arm 500. In some embodiments, a holder 502 is located at any position along a length of an arm 500. In some embodiments, a location of a holder 502 along a length of an arm 500 is adjustable. In some embodiments, a housing or tubing 504 is configured to house one or more wiring components 503. In some embodiments, a wiring component 503 operatively connects a sensor array to one or more components, such as a computer or power source. The arm 500, in some embodiments, comprises a first and second end. In some embodiments, a first end of the arm 500 is configured to be coupled to the sensor array 509. The first end is coupled to the sensor array by a pivot 505. In some embodiments, a pivot 505 provides one or more degrees of freedom of movement to the sensor array 509. In some embodiments, a position of a sensor array is adjusted by employing an actuator, such as a motorized button 506. The actuator, in some embodiments, adjusts a linear motion of the sensor array such as towards or away from a surface of an individual. In some embodiments, the actuator has a separate power button 507. In some embodiments, the motorized button 506 and the power button are the same. In some embodiments, the actuator comprises a bar or a handle 508. The bar is configured for manual adjustment of the arm 500 position, the sensor array position, or a combination thereof.

In some embodiments, a mobile cart device is configured to transition from an extended configuration as shown in FIG. 7 to a collapsed configuration as shown in FIG. 6 . In some embodiments, a mobile cart device is configured to transition between two configurations one or more times. In some embodiments, a mobile cart device is configured for a user to manually transition the device between two configurations. In some embodiments, a mobile cart device is configured for automatic transition between two configurations, such as automated by a motor system operatively coupled to a controller.

FIG. 6 shows an exemplary mobile cart device 600 in a collapsed configuration. As shown in FIG. 6 , a mobile cart device 600 comprises a sensor array 604, such as an optically pumped magnetometer. The sensor array 604 is coupled to a first end of an arm 608. In some embodiments, a second end of the arm 608 is coupled at location 607 to a top end of a vertical beam 602 or frame. The coupling, in some embodiments, comprises a pivot. In some embodiments, a pivot coupling is configured to transition the device 600 from an extended configuration to a collapsed configuration. In some embodiments, a cross beam 601 is coupled at location 609 to the arm 608 at any position between the first end and the second end. In some embodiments, a cross beam 601 is coupled to the arm 608 at a midpoint between the first end and the second end of the arm 608. In some embodiments, the cross beam 601 comprises a pivot, such as a pivot positioned at a midpoint along the cross beam 601. In some embodiments, a cross beam pivot is configured to transition the device 600 from an extended configuration to a collapsed configuration. In some embodiments, a cross beam 601 is configured to bend or to pivot such that the first end coupled to the sensor array 604 is moved towards a bottom end of the vertical beam 602. One or more pivots of a device 600 are locked in a configuration, such as an extended configuration or a collapsed configuration, such as by a locking element at position 607 or 601, or both.

In some embodiments, a mobile cart device 600 comprises a handle 610, such as a handle that is coupled to the arm 608. The handle 610, in some embodiments, facilitates actuation of the arm 608 to transition the device 600 between an extend configuration and a collapsed configuration. In some embodiments, a mobile cart device 600 in comprises one or more rotating elements (such as wheels 605 and 606) configured to rotate such that the mobile cart device 600 is moved. In some embodiments, a mobile cart device 600 comprises one or more anchoring elements (such as rubber feet 612 and 613) configured to secure the mobile cart device 600 in a desired location. In some embodiments, a mobile cart device 600 comprises a handle 611. In some embodiments, a handle 611 is configured to actuate one or more elements of the device 600. For example, a handle 611 is configured to actuate an arm 608 of the device 600 relative to the frame. In some embodiments, a handle 611 is configured to actuate a sensor array 604 relative to the arm 608. In some embodiments, a handle 611 translates a sensor array 604 in linear motion towards or away from an arm 608. In some embodiments, a handle 611 is configured to rotate. In some embodiments, a handle 611 is operatively coupled to a drive screw 603 for translating rotational motion of the handle 611 to linear motion of the sensor array 604.

FIG. 7 shows an exemplary mobile cart device 700 similar to FIG. 6 and in an extended configuration. A device 700 comprises a sensor array 701, comprising one or more optically pumped magnetometer. The sensor array 701 is operatively coupled to a first end of an arm 706 of the device 700 by one or more shafts (such as a linear motion shaft 702). In some embodiments, a second end of the arm 706 is coupled at location 707 to one or more vertical beams (such as beam 709 and beam 710). The coupling located at location 707, in some embodiments, comprises a pivot. The coupling is configured to transition the arm 706 between an extended configuration and a collapsed configuration. In some embodiments, the coupling is configured to move the sensor array 701 towards and away from the vertical beam.

The arm 706, in some embodiments, comprises a handle 704, a handle 703, or both configured to actuate a portion of the device 700. For example, handle 704 is configured to move the arm 706 relative to the frame. Handle 703 is configured to move the sensor array 701 relative to the arm 706. A device 700, in some embodiments, comprises a cross beam 713. In some embodiments, a first end 705 of a cross beam 713 is coupled to the arm 706, at a position between the first end and the second end of the arm 706, such as a midpoint position. In some embodiments, a second end 711 of the cross beam 713 is coupled to the frame, such as to a vertical beam or a cross beam 713 positioned between two vertical beams. A cross beam 713, in some embodiments, comprises a pivot 708. In some embodiments, a pivot is positioned at a midpoint on the cross beam 713. In some embodiments, a pivot 708 is configured to bend. In some embodiments, a pivot 708 is configured to transition the device between a collapsed configuration and an extended configuration. In some embodiments, a pivot 708 is reversibly lockable. A device 700, in some embodiments, comprises one or more rotating elements, such as a wheel 712, configured to move the device between locations.

FIG. 8 shows an exemplary computer system 801 that is programmed or otherwise configured to direct operation of a device or system as described herein, including movement of a base unit, movement of a shield, movement of a mobile cart, movement of a sensor array, acquisition of a measurement, comparison of a measurement to a reference measurement, or any combination thereof. The computer system 801 regulates various aspects of (a) movement of one or more device or system components, (b) operation of one or more sensors, (c) adjustment of one or more parameters of a sensor, (d) computationally evaluation of one or more measurements of a device or system, (e) display of various parameters including input parameters, results of a measurement, or any combination of any of these. In some embodiments, a computer system 801 is an electronic device of a user (e.g. smartphone, laptop) or, in some embodiments, is remotely located with respect to the electronic device. The electronic device, in some embodiments, is a mobile electronic device.

The computer system 801 includes a central processing unit (CPU, also “processor” and “computer processor” herein) 805, which, in some embodiments, is a single core or multi core processor, or a plurality of processors for parallel processing. The computer system 801 also includes memory or memory location 810 (e.g., random-access memory, read-only memory, flash memory), electronic storage unit 815 (e.g., hard disk), communication interface 820 (e.g., network adapter) for communicating with one or more other systems, and peripheral devices 825, such as cache, other memory, data storage and/or electronic display adapters. The memory 810, storage unit 815, interface 820 and peripheral devices 825 are in communication with the CPU 805 through a communication bus (solid lines), such as a motherboard. The storage unit 815 is configured as a data storage unit (or data repository) for storing data. The computer system 801 is operatively coupled to a computer network (“network”) 830 with the aid of the communication interface 820. The network 830 is the Internet, an internet and/or extranet, or an intranet and/or extranet that is in communication with the Internet. The network 830 in some embodiments is a telecommunication and/or data network. The network 830 includes one or more computer servers, which enable distributed computing, such as cloud computing. The network 830, in some embodiments, with the aid of the computer system 801, implements a peer-to-peer network, which enables devices coupled to the computer system 801 to behave as a client or a server.

The CPU 805 is configured to execute a sequence of machine-readable instructions, which are be embodied in a program or software. The instructions are stored in a memory location, such as the memory 810. The instructions are directed to the CPU 805, which is subsequently program or otherwise configure the CPU 805 to implement methods of the present disclosure. Examples of operations performed by the CPU 805 include fetch, decode, execute, and writeback.

The CPU 805 is part of a circuit, such as an integrated circuit. One or more other components of the system 801 are included in the circuit. In some embodiments, the circuit is an application specific integrated circuit (ASIC).

The storage unit 815 stores files, such as drivers, libraries and saved programs. The storage unit 815 stores user data, e.g., user preferences and user programs. The computer system 801 in some embodiments include one or more additional data storage units that are external to the computer system 801, such as located on a remote server that is in communication with the computer system 801 through an intranet or the Internet.

The computer system 801 communicates with one or more remote computer systems through the network 830. For instance, the computer system 801 communicates with a remote computer system of a user (e.g., a second computer system, a server, a smart phone, an iPad, or any combination thereof). Examples of remote computer systems include personal computers (e.g., portable PC), slate or tablet PC’s (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personal digital assistants. The user accesses the computer system 801 via the network 830.

Methods as described herein are implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system 801, such as, for example, on the memory 810 or electronic storage unit 815. The machine executable or machine readable code is provided in the form of software. During use, the code is executed by the processor 805. In some embodiments, the code is retrieved from the storage unit 815 and stored on the memory 810 for ready access by the processor 805. In some situations, the electronic storage unit 815 is precluded, and machine-executable instructions are stored on memory 810.

A machine readable medium, such as computer-executable code, takes many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) or the like, such as is used to implement the databases, etc. shown in the drawings. Volatile storage media include dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media takes the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer reads programming code and/or data. Many of these forms of computer readable media is involved in carrying one or more sequences of one or more instructions to a processor for execution.

The computer system 801, in some embodiments, includes or is in communication with an electronic display 835 that comprises a user interface (UI) 840 for providing, for example, a graphical representation of one or more signals measured, one or more reference signals, one or more parameters that is input or adjusted by a user or by a controller, or any combination thereof. Examples of UI’s include, without limitation, a graphical user interface (GUI) and web-based user interface.

Methods and systems of the present disclosure are, in some embodiments, implemented by way of one or more algorithms. An algorithm, in some embodiments, is implemented by way of software upon execution by the central processing unit 805. The algorithm is, for example, comparing a signal to a reference signal.

FIGS. 9A-9B show an example of a shield. In some embodiments, a shield has a first end and a second end. A first end of a shield, in some embodiments, comprises a closed taper end 901 a or 901 b. In some embodiments, a second end of the shield comprises an open end 904, substantially cylindrical in shape. In some embodiments, the opening of the second end is configured to receive at least a portion of an individual, a sensor array, a base unit, or any combination thereof into the shield. In some embodiments, a shield is monolith. In some embodiments, a shield is formed of one or more segments, such as a first segment 901 a or 901 b, a second segment 902 a or 902 b, and a third segment 903. In some embodiments, a shield comprises one layer. A shield, in some embodiments, comprises more than one layer. A shield, in some embodiments, comprises an inner layer 905. A shield, in some embodiments, comprises a spacing 906 between two layers.

FIGS. 10A-10B show an exemplary engineering drawing of the shield that is shown in FIGS. 9A-9B. As shown in FIG. 10A, a cross-sectional view of the shield demonstrates an example of suitable geometrical dimensions for a shield. The shield is shown as the cylindrical portion of the picture, with supports below comprising nylon, though attachments and supports is constructed of any nonferrous material known in the art. FIG. 10 B shows the longitudinal view of the same sample shield. In some embodiments, a shield has an overall length of from about 2000 millimeters (mm) to about 2500 mm or from about 2200 mm to about 2300 mm (such as about 2272.5 mm), an inner length of from about 1500 mm to about 2000 mm or from about 1700 mm to about 1800 mm (such as about 1750.0 mm), an inner layer with diameter of from about 500 mm to about 1000 mm or from about 700 mm to about 900 mm (such as about 800.0 mm), a middle layer with diameter of from about 600 mm to about 1100 mm or from about 800 mm to about 950 mm (such as about 883.0 mm), and an outer layer with diameter of from about 700 mm to about 1200 mm or from about 900 mm to about 1050 mm (such as about 986.0 mm), as indicated by FIGS. 10A-10B.

A shield, in some embodiments, comprises more than one layer with spacing between any two given layers. In some embodiments, a shield has non-uniform spacing between any two layers. Different sets of layers, in some embodiments, have non-uniform spacing relative to each other.

A layer of a shield or portion thereof, in some embodiments, comprises a thickness from about 0.1 to about 10 millimeters. In some embodiments, a layer of a shield has a thickness from about 0.5 to about 5 millimeters. In some embodiments, a layer of a shield has a thickness from about 0.1 to about 2 millimeters. In some embodiments, a layer of a shield has a thickness from about 0.8 to about 5 millimeters. A thickness is substantially the same along a length or a circumference of a shield. In some embodiments, a thickness of a layer of a shield varies along a length or circumference of a shield.

In some embodiments, a shield comprises a plurality of layers. In some embodiments, a space is present between at least two layers of the plurality of layers. In some embodiments, a space is present between each layer of the plurality of layers. In some embodiments, a space is present between a subset of layers of the plurality of layers. In some embodiments, a first layer of a shield is configured to be adjacent a second layer of a shield. In some embodiments, a first layer of a shield is configured to be attached or bonded to a second layer of a shield. In some embodiments, a first layer of a shield is configured to be positioned from about 0.1 inches to about 5 inches from a second layer. In some embodiments, a first layer of a shield is configured to be positioned from about 1 inch to about 3 inches from a second layer. In some embodiments, a first layer of a shield is configured to be positioned from about 1 inch to about 20 inches from a second layer. In some embodiments, a first layer of a shield is configured to be positioned from about 1 inch to about 10 inches from a second layer.

In some embodiments, a length of a shield, such as an internal length or an external length, is about 2x an internal diameter of a shield. In some embodiments, a length of a shield is from about 0.5x to about 3x an internal diameter of a shield. In some embodiments, a length of a shield is from about 1x to about 3x an internal diameter of a shield. In some embodiments, a length of a shield is from about 1.5x to about 3x an internal diameter of a shield.

In some embodiments, as shown in FIGS. 11A-11L, the layers of the shield are separated using spacers of variable width, height, and length depending on the application of interest. In some embodiments, the spacers used to separate layers of the shield take the form of an arc. In some embodiments, spacers are used to cover a portion or the entire circumference of two consecutive layers. In some embodiments, spacers cover only part of the circumference of two consecutive layers.

In some embodiments, as shown in FIGS. 12A-12B, a shield support is manufactured in one or more pieces and is configured to be operatively connected (such as joined) by way of bolts, fasteners, screws, or any combination thereof. In some embodiments, a shield support is operatively connected (such as attached) to a shield by one or more: fasteners, bolts, screws, or any combination thereof. In some embodiments, a support is also attached using an adhesive fastener. In some embodiments, as seen in FIG. 12A, a shield spacer is positioned anywhere along the circumference of two consecutive layers. In some embodiments, a system of one or more hooks is operatively connected (such as attached) to any surface of any layer of the shield by an adhesive, a fastener, a screw, a bolt, or any combination thereof. A layer, comprises a protective layer. An inner layer, a middle layer, an outer layer, or any combination thereof, in some embodiments, comprises a protective layer. In some embodiments, a portion of a layer comprises a protective layer. A protective layer, in some embodiments, comprises a nonferrous material. A protective layer, in some embodiments, comprises polyvinyl chloride plastic. In some embodiments, a protective layer spans the entire interior surface of a shield. In some embodiments, protective layer spans part of an interior surface of a shield.

FIG. 13 , shows an exemplary hook 1300 configured to span a portion of or an entire volume of a shield. In some embodiments, one or more hooks 1300 are operatively connected to a wiring (such as holding a wiring) and is designed to transmit analog electrical signals, digital electrical signals, or a combination thereof. In some embodiments, one or more hooks 1300 are positioned along a single plane of a shield. In some embodiments, hooks 1300 are positioned along more than one plane of a shield. Hooks are positioned along multiple planes. In some embodiments, hooks 1300 are positioned on an inside surface of a shield. In some embodiments, hooks 1300 are positioned circumferentially about a shield at a single cross section. In some embodiments, hooks 1300 are positioned circumferentially about a shield and continuing along a length of a shield. In some embodiments, hooks 1300 are configured to hold an electrical coil system, such as an electrical coil system designed to eliminate an accumulated magnetic field. In some embodiments, hooks 1300 are configured to hold an electrical coil system, such as an electrical coil system designed to create a homogenous magnetic environment inside a shield. In some embodiments, an electrical coil system is configured to employ the use of a wire of variable gauge. An exemplary wire gauge suitable for use with devices and systems described herein is 28 AWG shown in FIG. 13 .

As shown in FIGS. 14A-14B, a mobile cart device, in some embodiments, is capable of operation in a non-magnetically shielded environment. In some embodiments, a computer, electronics, or combination thereof is housed on the mobile cart device itself. In some embodiments, an electronic control module is housed in a compartment (such as a cabinet) of the mobile cart device. In some embodiments, a mobile cart is configured to be powered by a battery (such as a mobile battery). In some embodiments, a device’s arm is configured for motorized movement in one or more degrees of freedom.

One example of a mobile cart device 1400 is shown in FIGS. 14A-14B. This example is similar to the example shown in FIG. 4 . A device or system as described herein, in some embodiments, comprises a base unit (such as a mobile base unit) and an array of sensors, (such as an optically pumped magnetometer). In some embodiments, the array of sensors is housed in a housing 1404. In some embodiments, the housing 1404 is interchangeable. In some embodiments, the housing 1404 is universally configured to accommodate more than one sensor array configuration. In some embodiments, the housing 1404 is configured to be removable and replaced with a different housing. In some embodiments, the housing 1404 comprises a motor feature 1403, such that an adjusted of a sensor array position is adjusted by pressing the motor feature 1403 on the housing 1404. In some embodiments, the adjustment is automated. In some embodiments, the adjustment is performed manually by a user pressing the motor feature 1403. A base unit, in some embodiments, comprises a structure, such as an arm, a beam, a rod or a protrusion that is configured to allow a user to adjust a position of the array. In some embodiments, the arm is configured to be associated with the sensor array or the housing 1404, such as associated with a bracket 1402. In some embodiments, the arm is extendible. In some embodiments, the arm is movable in one or more degrees of freedom. In some embodiments, a position of an arm, such as an extended arm position, is secured by a locking component 1401. In some embodiments, a locking component 1401, such as a locking solenoid, is positioned on the arm. In some embodiments, a locking component 1401 is operatively integrated with the motor feature 1403. A base unit, in some embodiments, comprises a single compartment 1405. A base unit, in some embodiments, comprises two compartments. A base unit, in some embodiments, comprises a plurality of compartments. In some embodiments, a compartment 1405 is configured to house one or more components. For example, a compartment 1405 is configured to house a power source, such that a base unit is not restricted to remain proximal to a wall outlet or external power source. In some embodiments, a compartment 1405 is configured to house a computer including an operating system, a database, a monitor, a graphical user interface, or any combination thereof. In some embodiments, a compartment 1405 is configured to house one or more sensors or a housing for a sensor. In some embodiments, a compartment 1405 is configured to house a power source, a computer, one or more sensors, a housing for a sensor, wiring, or any combination thereof. A base unit, in some embodiments, comprises a surface, such as a flat surface. In some embodiments, the surface is configured to hold a computer or other component of the system. A base unit, in some embodiments, comprises one or more rotating elements. In some embodiments, a rotating element comprises a wheel, a roller, a conveyor belt, or any combination thereof configured to provide movement of a base unit. A base unit, in some embodiments, comprises an arm. One end of an arm is configured to associate with the array of sensors. In some embodiments, a second end of an arm is configured to associate with the base unit, at for example a compartment 1405 or a surface. In some embodiments, an arm is adjustable. For example, an arm is extendible in length, such as a first portion of an arm that extends from a second portion of an arm. A base unit, in some embodiments, comprises wiring, such as one or more wires. Wiring is configured to associate with one or more sensors of an array, one or more power sources of the base unit, one or more computers of the base unit, or any combination thereof. A base unit, in some embodiments, comprises a shield, such as a disposable shield or a modular shield. In some embodiments, a shield is separate from a base unit. In some embodiments, a shield is associated with a base unit, such as attached to a base unit as a position that is proximal the array. In some embodiments, a shield is integral to the base unit. In some embodiments, a shield, an array, an arm, or any combination thereof is operatively connected (such as by wiring or wirelessly) to a controller or computer system.

FIG. 15A is an enlarged view of one example of the sensor array 1500 a. The sensor array, 1500 a in some embodiments, comprises one or more sensor plates. For example, a sensor array 1500 a, in some embodiments, comprises a bottom sensor plate 1501. In some embodiments, the bottom sensor plate 1501 is secured to other sensor components by one or more mounting bolts, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 mounting bolts. The sensor array 1500 a, in some embodiments, comprises a top sensor plate 1502. In some embodiments, the top sensor plate 1502 is secured to other sensor components by one or more mounting bolts, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 mounting bolts. The sensor array 1500 a, in some embodiments, comprises one or more sensor plate standoffs 1503. For example, a sensor array 1500 a, in some embodiments, comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 sensor plate standoffs.

A sensor array 1500 a, in some embodiments, comprises one or more sensors 1506. In some embodiments, a sensor comprises a magnetometer sensor. A sensor, in some embodiments, comprises an optically pumped vector magnetometer or a zero field magnetometer. A sensor, in some embodiments, comprises a superconducting quantum interference device (SQUID), an inductive pickup coil, a vibrating sample magnetometer (VSM), a pulsed field extraction magnetometer, a torque magnetometer, a Faraday force magnetometer, an optical magnetometer, or any combination thereof. A sensor, in some embodiments, comprises a small-scale microelectricalmechanical (MEMS)-based magnetic field sensor.

In some embodiments, a sensor does not comprise a housing. In some embodiments, one or more sensors 1506 of a sensor array 1500 a comprises one or more sensor housings 1504 a or 1504 b. For example, a sensor array 1500 a, in some embodiments, comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 or 24 sensor housings. In some embodiments, the sensor array 1500 a comprises a sensor housing for each sensor in the array. In some embodiments, the sensor array 1500 a comprises a sensor housing for at least every two sensors in the array. In some embodiments, a sensor housing is non-adjustable. In some embodiments, a sensor housing is movable within a sensor array unit to accommodate more than one sensor array configuration. In some embodiments, a sensor housing is secured in a location by one or more mounting bolts. In some embodiments, a sensor array 1500 a is secured in a location by a sensor housing cap 1505.

In some embodiments, a sensor array 1500 a comprises a handle 1510. In some embodiments, actuation of the handle 1510, such a rotational motion causes motion (such as linear motion) of the sensor array 1500 a (i) away or towards an individual, (ii) away or towards an arm of the mobile cart device, or (iii) a combination thereof. The handle 1510 is operated manually. In some embodiments, actuation of the handle 1510 is automated. In some embodiments, when the handle 1510 is actuated, a screw 1509, such as a lead screw rotates. Rotation of the screw 1509, in some embodiments, permits one or more shafts on the sensor array to move.

A sensor, in some embodiments, comprises an element 1512 for coupling of two or more shafts 1508 a or 1508 b (such as shaft 1508 a (such as a linear motion shaft) and shaft 1511 (such as a square motion transfer shaft), for transmission of motion (such as linear motion of the sensor array away or towards an individual). In some embodiments, the shaft also comprises a stopping element, such as a dog clutch. In some embodiments, the element 1512 is operatively coupled to the handle 1510, the screw 1509, one or more shafts such as shaft 1508 a and shaft 1511, or any combination thereof.

A sensor array 1500 a, in some embodiments, comprises a bracket 1507, such as a support bracket. In some embodiments, the bracket provides a spatial orientation for one or more shafts and one or more screws of the sensor array relative to one another. In some embodiments, a bracket is operatively coupled to a shaft 1508 a, a shaft 1511, a screw 1509, an element 1512, or any combination thereof.

A sensor array 1500 a, in some embodiments, comprises a stopper 1513, such as an individual stopper. In some embodiments, the stopper 1513 is configured to be positioned at a surface of an individual. In some embodiments, the stopper 1513 is configured to be positioned at a specified distance away from a surface of an individual. In some embodiments, the stopper 1513 is configured to prevent the sensor array from advancing beyond a specified position, such as beyond a surface of an individual. In some embodiments, a stopper 1513 is positioned on surface of the sensor array that when in operation is positioned closest to the subject.

One example of a mobile cart device 1500 b is shown in FIG. 15B. This example is similar to the example shown in FIG. 6 and FIG. 7 . A mobile cart device 1500 b, in some embodiments, comprises an arm 1514. The arm 1514, in some embodiments, comprises a first end and a second end. In some embodiments, a sensor array is coupled to the first end of the arm 1514. In some embodiments, an opposite end of the arm 1514 is coupled to a frame having a first supporting beam 1517 a and a second support beam 1517 b. In some embodiments, the opposite end of the arm 1514 is coupled to the frame at an upper bracket 1518 of the frame. In some embodiments, the mobile cart device 1500 b comprises a second arm. In some embodiments, the second arm comprises a top support arm 1515 and a bottom support arm 1516. In some embodiments, at a location between a first end and second end of the arm 1514, a first end of a second arm is coupled to the arm 1514. In some embodiments, a second end of the second arm is coupled to the frame, such as coupled to the frame at a bracket 1519 (such as a locker bracket) of the frame. In some embodiments, the mobile cart device 1500 b comprises one or more rotating elements, such as a wheel 1522. In some embodiments, a rotating element is operatively coupled to one or more axels 1521 (such as two rotating elements operatively coupled to a single axel), one or more bearings 1523, or a combination thereof, such that rotation of the two rotating elements occur in tandem. In some embodiments, the mobile cart device 1500 b comprises two rotating elements. In some embodiments, the mobile cart device 1500 b comprises one rotating element. In some embodiments, a rotating element is configured to move the mobile cart device 1500 b from one location to a different location. A mobile cart device 1500 b, in some embodiments, comprises an anchoring element 1524, such as a rubber foot, to anchor a mobile cart device 1500 b at a desired location or to prevent further movement of the rotating element. A mobile cart device 1500 b, in some embodiments, comprises one anchoring element. A mobile cart device 1500 b, in some embodiments, comprises more than one anchoring element, such as two or three anchoring elements. One or more rotating elements, axels, anchoring elements, or any combination thereof is operatively coupled to the mobile cart device 1500 b by one or more mounts 1520.

In some embodiments, a mobile cart device 1500 b switches configuration from an extended configuration (FIG. 15B) to a closed configuration (FIG. 15C). In embodiments comprising an extended configuration, an arm 1514 is collapsed adjacent a frame, such that the mobile cart device is stored or easily moved to a different location.

In some embodiments, performance of a magnetometer is improved with equilibration. In these embodiments, a gradient of 1 nT/m is achieved within the shield. Equilibration, in some embodiments, comprises the process of degaussing.

In some embodiments, a shield configured for utilization of the equilibration process comprises an arrangement of coils. Typically the coils are arranged in one or more layers. In some embodiments, a shield comprises an inner coil layer and one or more outer coil layers, inner coils for an innermost layer and outer coils for each of the outer layers.

In some embodiments, the inner coils are (for 90 cm diameter of the cylinders) distributed in 45 degrees to effectively form 8 coils. The mechanical mounting precision is about +/- 2 cm per wire. Many different configurations are acceptable for the outer coils generally. In some embodiments, a shield comprises 1 outer coil. In some embodiments, a shield comprises 2 outer coils. In some embodiments, a shield comprises 3 outer coils. In some embodiments, a shield comprises 4 outer coils. In some embodiments, a shield comprises 5 outer coils. In some embodiments, a shield comprises 6 outer coils. In some embodiments, a shield comprises 7 outer coils. In some embodiments, a shield comprises 8 outer coils. In some embodiments, a shield comprises 9 outer coils. In some embodiments, a shield comprises 10 outer coils.

In some embodiments, at least the inner layer must be electrically isolated. In some embodiments, ESD PVC is used instead of regular plastic just to avoid charge up effects, which disturb the magnetometers.

FIG. 22 shows an exemplary layout of one inner coil 2200 positioned in an embodiment of a shield. FIG. 23 shows an exemplary layout of outer coils 2300 positioned in an embodiment of a shield.

In some embodiments, a connection to an amplifier (or transformer) is opened during the measurements with the magnetic field probes. In some embodiments, this is achieved using a mechanical relay.

The wire dimensions are typically at least 2.5 mm2, but 4 mm2 would be preferable. I would suggest for the test device 3 turns at each 8th of the coil, resulting in 24 turns. I cannot estimate the permeability, but it should be comparable to Krupp Magnifer Material (which I am more used to). So the 24 turns would be about 1 Ohm and with 10 A saturation current, this gives 10 V..

In some embodiments, an equilibration sequence would be a 30 s sequence with linearly decreasing envelope, starting from saturation of the inner layer. This sequence is needed every time some large change in the field is applied. During regular operation I would guess 1-3 times a day would make sense. The outer shields must be equilibrated only once, when the shield is installed, or when the external fields change direction by 90 degrees or so, using the same amplifier. (Therefore, there must be a similar amount of turns for the coils, to use the same equipment).

In some embodiments, the coils for equilibration are individual wires with gold plated contacts. Due to magnetization issues, no Ni substrates or coatings can be used for connectors inside. In some embodiments, the required level of precision the equilibration coils of the outer shield can be placed randomly without special precautions, whereas the inner coils require at least a 6 fold symmetry for the distribution of the current to obtain a reasonably shaped residual field for 60 cm diameter and 8 for 1 m diameter. For the demonstrated project we chose connectors from brass with gold coating without a nickel intermediate layer (this is rare!) to avoid excessive magnetization. All connectors must be placed outside the inner shield layer. Their magnetization (on this level) is not relevant for the residual field inside.

An equilibration process employed in some embodiments of the shields described herein, is a process for bringing magnetizable material in an equilibrium with a surrounding magnetic field. In some embodiments, this is done by applying a sinusoidal current around a magnetizable material. The oscillation is extremely well centered around zero and is large enough to saturate the material in both directions. By decreasing the amplitude to zero, a very low magnetic field strength outside the magnetizable material (inside the cylinder) is obtained. For initial tests, a linearly decreasing envelope is useful, as it is a very reliable function. This model is programmed into the equilibration unit. An exponentially decreasing function may be advantageous in future. The pre-set function (which can be changed by the user on the PC) is shown below:

FIG. 24 shows a typical equilibration function. At the beginning, the maximum current is kept for 10 cycles and then decreased until zero amplitude is reached. Note that at the ultimate performance level, many options for changing and improvements are available.

In some embodiments, the equilibration coils are connected to the electrical equipment using twisted-pair cables. No RF shielding or other precautions are required, as higher frequencies are damped by the inductance of the shielding material and coil configuration (mH range).

In some embodiments, a computing device programs a sinusoidal function with envelope function, which is converted to a voltage signal by an NI 6281 data acquisition device. The voltage is fed to a voltage divider and then drives a power amplifier. The function can be set by the user and is programmable. The timing resolution of the curve is 10 kHz.

In some embodiments, inside the control box there is a box with potentiometers. These potentiometers can be adjusted manually to set the ratio of DAC voltage to current out of the amplifier. This minimizes any bit-size effects for the residual field (16 bit for 20 V = 0.3 mV resolution). From experience, the optimization of this will be relevant for < 0.5 nT residual fields. There are 2 potentiometers to tune different currents, they can then be selected via software. In case of a noisy environment, the voltage divider box is a useful place to add additional frequency filtering by a capacitor. In some embodiments, the band pass filtering of the amplifier will be sufficient for most applications.

In some embodiments, a power amplifier comprises a 4-quadrant amplifier which can be operated with large inductive loads and is intrinsically fail-safe against mistakes operation, e.g shortcuts, many inductive spikes etc.. For magnetic equilibration, the amplifier should be used in current-controlled mode, but can also be operated in any configuration. Due to extreme noise requirements, it is preferable to change the coils around the magnetizable material (cross section and number of turns) to match the maximum power of the amplifier. The power is chosen to be very small to achieve extremely low noise operation. Band-pass filters can be set manually on the front side to reduce noise effects. The amplifier can be fully remote controlled via a sub-d connector on the back side. A unique feature if this amplifier is the possibility to adjust the base-line by 1% via an analog +/- 10 V input, independent of the signal input.

In some embodiments, to perform DC measurements, the noise and the drift of the magnetic field probes is relevant. In some embodiments, two three-cannel Bartington Fluxgates type Mag03-IEL-70 with < 6 pT noise-amplitude (peak-to-peak) are employed. Two electronics units supply three sensors each, with flying lead sensors with 5 m cable length each. In some embodiments, a readout of, for example, one or more fluxgates is done with a NI 628118-bit analog input unit to provide sufficient resolution of the fluxgate analog signals (+/- 10 V). No voltage divider is required to match the range. The USB control is only for data transfer to the PC, the NI unit is independently grounded and has an independent power supply. In some embodiments, the readout rate is set up to 625.000 samples per second.

Assessment of Coronary Artery Disease

Also described herein is a method for determining a likelihood of a presence of coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) in an individual, the method comprising: identifying a first negative electromagnetic dipole and a first positive electromagnetic dipole in a first electromagnetic field map associated with a heart of the individual at a first time; identifying a second negative electromagnetic dipole and second positive electromagnetic dipole in a second electromagnetic field map associated with the heart of the individual at a second time; determining a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole; determining a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; and determining that there is the likelihood of the presence of the coronary artery disease in the individual if the first angle differs from the second angle by at least 100 degrees or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.

FIG. 25 shows an example method 2500 for assessing the presence of coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) in an individual. The method 2500 may comprise, for each of an R-wave electromagnetic field map and a T-wave electromagnetic field map, identifying a negative electromagnetic dipole and a positive electromagnetic dipole in the electromagnetic field maps (as in 2502). Next, the method 2500 may comprise determining a peak R-depolarization angle and a peak T-repolarization angle based on the electromagnetic dipoles of the R-wave and T-wave electromagnetic field maps, respectively (as in 2504). Next, the method 2500 may comprise determining the RT peak angle difference based on the absolute difference between the peak R-depolarization angle and the peak T-repolarization angle (as in 2506). Next, the method 2500 may comprise assessing the presence of coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) in the individual if the RT peak angle difference is at least 100 degrees (or either electromagnetic field map has a third electromagnetic dipole) (as in 2508).

In some embodiments, the method further comprises sensing, at the first time, a first electromagnetic field associated with the heart of the individual, and sensing, at the second time, a second electromagnetic field associated with the heart of the individual, wherein the first electromagnetic field map comprises a representation of the first electromagnetic field and the second electromagnetic field map comprises a representation of the second electromagnetic field.

As an example, the coronary artery disease may comprise cardiac ischemia (e.g., an occlusion of the left anterior descending artery). As another example, the coronary artery disease may comprise demand ischemia (e.g., hyperthyroidism, malignant hypertension, tachycardia, and sepsis).

In some embodiments, the first angle comprises a peak R-depolarization angle at the first time. The first time may be a time when an R-wave is recorded on the electrocardiogram. For example, the peak R-depolarization angle may be determined by determining a first line that passes through both the first negative electromagnetic dipole and the first positive electromagnetic dipole, and determining the angle between the first line and a horizontal axis.

In some embodiments, the second angle comprises a peak T-repolarization angle at the second time. The second time may be a time when a T-wave is recorded on the electrocardiogram. For example, the peak T-repolarization angle may be determined by determining a second line that passes through both the second negative electromagnetic dipole and the second positive electromagnetic dipole, and determining the angle between the second line and a horizontal axis.

In some embodiments, a third electromagnetic dipole is present in the first electromagnetic field map or the second electromagnetic field map. This is referred to as a multiple electromagnetic dipole on the first electromagnetic field map or the second electromagnetic field map.

In some embodiments, the likelihood of the presence of the coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) in the individual is determined to be present if the first angle differs from the second angle by at least 100 degrees (e.g., from 100 degrees to 170 degrees). In other words, a likelihood of coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) may be identified as present in the individual based on the RT peak angle difference being at least 100 degrees (e.g., falling in the range of 100 degrees to 170 degrees).

In some embodiments, the likelihood of the presence of the coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) in the individual is determined to be absent if the first angle differs from the second angle by less than 100 degrees (or either magnetic field map has a third electromagnetic dipole). In other words, a likelihood of coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) may be identified as absent in the individual based on the RT peak angle being less than 100 degrees (or either magnetic field map has a third electromagnetic dipole).

In some embodiments, the method further comprises recording an electrocardiogram of the individual. The individual may have either a normal electrocardiogram while experiencing chest pain or normal troponin level while experiencing chest pain. The individual may have had a positive stress test or abnormal echocardiogram findings. A stress test may be performed on the individual, if a likelihood of coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) is determined for the individual (e.g., if the first angle differs from the second angle or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map).

In some embodiments, the method further comprises determining a likelihood of a presence of a conduction abnormality in the heart of the individual if the first positive electromagnetic dipole and the second negative electromagnetic dipole have a same location or the first negative electromagnetic dipole and the second positive electromagnetic dipole have a same location. In some embodiments, the method further comprises treating the individual with a treatment for cardiac ischemia (e.g., regardless of the mechanism resulting in myocyte ischemia). For example, the treatment may comprise one or more of: a daily aspirin or ibuprofenregimen, a blood pressure lowering medication, a lipid lowering medication, a cardiac catheterization, a surgical intervention, or a combination thereof.

Also described herein is a non-transitory computer-readable medium comprising machine executable code that, upon execution by one or more computer processors, implements a method for determining a likelihood of a presence of coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) in an individual, the method comprising: identifying a first negative electromagnetic dipole and a first positive electromagnetic dipole in a first electromagnetic field map associated with a heart of the individual at a first time; identifying a second negative electromagnetic dipole and second positive electromagnetic dipole in a second electromagnetic field map associated with the heart of the individual at a second time; determining a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole; determining a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; and determining that there is the likelihood of the presence of the coronary artery disease (e.g., cardiac myocyte ischemia with or without associated epicardial coronary artery disease) in the individual if the first angle differs from the second angle by at least 100 degrees or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.

FIGS. 26A-26B show an example of how methods and systems of the present disclosure may be used to analyze an electric current of an organ or tissue (e.g., a heart) of a subject and determine its associated magnetic field, including a depiction of Ampere’s Law (FIG. 26A) and an example of a magnetic field map generated from the electric current (FIG. 26B). FIG. 26A shows that according to Ampere’s Law, an electric current I that is traveling through a long and straight wire generates a magnetic field B surrounding the wire, according to the right-hand rule. FIG. 26B shows an example of a magnetic field map generated from the electric current according to systems, devices, and methods of the present disclosure, including color-coded intensities of current vectors that are indicative of a negative electromagnetic dipole 2602 (shown in blue), a positive electromagnetic dipole 2604 (shown in red), and areas of zero magnetic field 2606 corresponding to the current source (shown in green). Alternatively, any colors may be arbitrarily chosen to represent color-coded intensities of current vectors that are indicative of positive and negative electromagnetic dipoles, and the areas of zero magnetic field corresponding to the current source.

FIGS. 27A-27B show an example of how methods and systems of the present disclosure may be used to analyze an electric current of an organ or tissue (e.g., a heart) of a subject and determine its associated magnetic field, including a depiction of a peak R-depolarization angle 2702 (FIG. 27A) and a depiction of a peak T-repolarization angle 2704 (FIG. 27B), where an increased R-T angle gap is indicative of cardiac ischemia in the heart of the subject.

As shown in FIG. 27A, the peak R-depolarization angle may be determined from a magnetic field map generated during the period of time that the R-wave (and corresponding R-peak) is measured using an ECG. The R-peak of the magnetic field map represents the aggregate depolarization of the heart.

The interpretation of magnetic field maps may comprise identifying positive magnetic poles (e.g., shown in red) and negative magnetic poles (e.g., shown in blue) during the duration of the R-wave. For example, the positive magnetic pole may be determined as the center (e.g., centroid) of the positive magnetic field values, while the negative magnetic pole may be determined as the center (e.g., centroid) of the negative magnetic field values. A first vector may be defined between the positive magnetic pole and the negative magnetic pole, for purposes of determining an angle therefrom. Alternatively, a first line, a line segment, or a ray may be defined between the positive magnetic pole and the negative magnetic pole, for purposes of determining an angle therefrom. A second vector may be defined as a horizontal vector (e.g., having the same direction as the positive x-axis), for purposes of determining an angle therefrom. Alternatively, a second line, a line segment, or a ray may be defined that is parallel to a horizontal vector (e.g., having the same direction as the positive x-axis), for purposes of determining an angle therefrom. Without loss of generality, the second vector, line, line segment, or ray may pass through the negative magnetic pole (shown in blue). Alternatively, the second vector, line, line segment, or ray may pass through another point (e.g., any point between the positive and negative magnetic poles) without affecting the determination of the angle therefrom. The first vector and/or the second vector may be expressed using any suitable coordinate system, including but not limited to, a 2-D Cartesian coordinate, a 3-D Cartesian coordinate system, a rectangular coordinate system, a parametric coordinate system, and a polar coordinate system.

After determining the first vector and the second vector, a vector angle may be defined based on the positive and negative magnetic poles at a given time. The vector angle may represent an angle between the first vector and the second vector. The vector angle may be determined as the smallest angle change between the first vector and the second vector. For example, the vector angle may have a value ranging from 0 to 360 degrees, or equivalently may have any integer multiple of 360 added or subtracted therefrom to arrive at a value ranging from 0 to 360 degrees. As an example, the vector angle θ may be determined using the following expression: cos(θ) = a · b / (|a| |b|), where a and b denote the first vector and the second vector, respectively, “·” denotes a vector dot product, and “| |” denotes a vector magnitude. The peak R-depolarization angle may be determined as the vector angle of a magnetic field map associated with the period of time that the R-wave (and corresponding R-peak) occurs (e.g., which may be measured using an ECG).

In some embodiments, a computer-implemented algorithm may be performed to determine one or more of the positive magnetic electromagnetic dipole(s), the negative magnetic electromagnetic dipole(s), the first vector, the second vector, and the vector angle based on analysis of a magnetic field map. The computer-implemented algorithm may determine the vector angle with or without explicitly generating one or more of the positive magnetic electromagnetic dipole(s), the negative magnetic electromagnetic dipole(s), the first vector, and the second vector.

As shown in FIG. 27B, the peak T-repolarization angle may be determined from a magnetic field map generated during the period of time that the T-wave (and corresponding T-peak) is measured using an ECG. The T-peak of the magnetic field map represents the aggregate repolarization of the heart.

The interpretation of magnetic field maps may comprise identifying positive magnetic poles (e.g., shown in red) and negative magnetic poles (e.g., shown in blue) during the duration of the T-wave. For example, the positive magnetic pole may be determined as the center (e.g., centroid) of the positive magnetic field values, while the negative magnetic pole may be determined as the center (e.g., centroid) of the negative magnetic field values. A first vector may be defined between the positive magnetic pole and the negative magnetic pole, for purposes of determining an angle therefrom. Alternatively, a first line, a line segment, or a ray may be defined between the positive magnetic pole and the negative magnetic pole, for purposes of determining an angle therefrom. A second vector may be defined as a horizontal vector (e.g., having the same direction as the positive x-axis), for purposes of determining an angle therefrom. Alternatively, a second line, a line segment, or a ray may be defined that is parallel to a horizontal vector (e.g., having the same direction as the positive x-axis), for purposes of determining an angle therefrom. Without loss of generality, the second vector, line, line segment, or ray may pass through the negative magnetic pole (shown in blue). Alternatively, the second vector, line, line segment, or ray may pass through another point (e.g., any point between the positive and negative magnetic poles) without affecting the determination of the angle therefrom. The first vector and/or the second vector may be expressed using any suitable coordinate system, including but not limited to, a 2-D Cartesian coordinate, a 3-D Cartesian coordinate system, a rectangular coordinate system, a parametric coordinate system, and a polar coordinate system.

After determining the first vector and the second vector, a vector angle may be defined based on the positive and negative magnetic poles at a given time. The vector angle may represent an angle between the first vector and the second vector. The vector angle may be determined as the smallest angle change between the first vector and the second vector. For example, the vector angle may have a value ranging from 0 to 360 degrees, or equivalently may have any integer multiple of 360 added or subtracted therefrom to arrive at a value ranging from 0 to 360 degrees. As an example, the vector angle θ may be determined using the following expression: cos(θ) = a · b / (|a| |b|), where a and b denote the first vector and the second vector, respectively, “·” denotes a vector dot product, and “| |” denotes a vector magnitude. The peak T-repolarization angle may be determined as the vector angle of a magnetic field map associated with the period of time that the T-wave (and corresponding T-peak) occurs (e.g., which may be measured using an ECG).

FIG. 28 shows how the heart generates electricity, including depolarization ion flow (non-energy dependent), in which (1) sodium slows its entering into the cell and potassium leaves the cell, and (2) large amounts of calcium enter the cell; repolarization ion flow (highly energy dependent), in which (3) calcium stops entering the cell and potassium leaves the cell, and (4) restored balance of the ions inside and outside of the cell (repolarized); and heart attack/ischemic cells, where the damaged cells are stuck at Zone 3 (depolarized) and can no longer contract.

FIG. 29 shows a “Wiggers Diagram” depicting the cardiac cycle, showing ventricular volume, ventricular pressure, aortic pressure, and atrial pressure, which shows that electrical generation precedes mechanical function of the heart.

FIG. 30 shows an example of assessment of patient intake using systems, devices, and methods of the present disclosure, including patients with stress testing, patients with negative MCG or positive MCG, patients with negative ST or positive ST, and patients with positive CA or negative CA. In this example, 97 total patients are presented to the clinic and undergo stress testing for further evaluation, of which 90 patients have a negative MCG result and 7 patients have a positive MCG result.

Of the 90 patients with a negative MCG result, 81 patients have a negative ST result, and 9 patients have a positive ST result. Of the 9 patients have a positive ST result, 4 patients have a positive CA result, and 5 patients have a negative CA result. Further, of the 7 patients with a positive MCG result, 4 patients have a positive ST result, and 3 patients with a negative ST result. Of the 4 patients with a positive ST result, 3 patients have a positive CA result, and 1 patient has a negative CA result. Of the 3 patients with a negative ST result, all 3 patients have a negative CA result.

As a result of the above results, 81 patients are determined to likely have early discharge, a small number still need stress test for unstable angina before disposition decision; and 16 false positive cases are removed, leaving only 2 false positive cases; the remainder of the cases need therapy. Therefore, there is no acute ischemia eligible for early discharge and elective outpatient evaluation.

FIG. 31 shows an example of a workflow for chest pain triage according to a clinical standard of care. After a patient having chest pain symptoms presents to the emergency department, the patient undergoes a clinical history and physical examination, ECG tests, and a first troponin draw for a troponin test. The patient then has a 17% chance of being given a high risk for cardiac ischemia with or without epicardial coronary artery disease (CAD) based on a HEART score of 7 to 10, a 47% chance of being given an intermediate risk for cardiac ischemia based on a HEART score of 4 to 6, and a 36% chance of being given a low risk for cardiac ischemia based on a HEART score of 0 to 3. The patient undergoes catheterization treatment if given a high risk score. Conversely, the patient is discharged if given a low risk score. However, about 70% of the time, the patient undergoes stress test, CTA, and other cardiac imaging tests. This produces no improvement in outcomes, since nearly 200 thousand ACS patients in the U.S. are missed in the emergency department, and have a major adverse cardiac event (MACE) within 30 days. The average time for diagnosis may take 8 to 10 hours for the HEART risk score assessment, and up to 14 hours if the patient undergoes stress test, CTA, and other cardiac imaging tests. Therefore, the patient is typically not discharged until 8 to 24 hours after presenting to the emergency department.

FIG. 32 shows an example of an improved workflow for chest pain triage according to systems, devices, and methods of the present disclosure. After a patient having chest pain symptoms presents to the emergency department, the patient undergoes a clinical history and physical examination, ECG tests, and a first troponin draw for a troponin test. The patient then has a 17% chance of being given a high risk for cardiac ischemia with or without epicardial coronary artery disease (CAD) based on a HEART score of 7 to 10, a 47% chance of being given an intermediate risk for cardiac ischemia based on a HEART score of 4 to 6, and a 36% chance of being given a low risk for cardiac ischemia with or without epicardial based on a HEART score of 0 to 3. If given a high risk score, the patient is admitted, given intravenous heparin with or without nitro, and then undergoes catheterization treatment. Conversely, if given a low or intermediate risk score, the patient is confirmed to have a negative result using MCG imaging and analysis systems, devices, and methods of the present disclosure, and then the patient is discharged. This reduces the need for additional and often unnecessary stress testing, CTA, and other cardiac imaging tests. As a result, the MCG imaging and analysis systems, devices, and methods of the present disclosure are positioned for low and intermediate risk chest pain patients, where ACC/AHA guidelines do not require observation stays and/or stress testing/CTA. This may enable time-to-discharge to improve by 6 to 20 hours per patient.

EXAMPLES

Non-limiting examples of embodiments and elements of embodiments of the methods, devices, and systems described herein are provided as follows.

Example 1

-   A magnetically shielded environment: comprises minimum dimensions of     about 7 foot width x about 7 foot depth x about 7 foot height. A     magnetically shielded environment, in some embodiments, comprises a     DC shielding factor of at least about 500 with minimum shielding     factor of about 56 decibel (dB) from a bandwidth of from about 0.1     Hz to about 500 Hz at all points at least about 1 foot from each     surface of a magnetically shielded environment. -   · A cart with a computer: is stationed outside of the magnetically     shielded environment. Connected to the computer is a sensor’s     electronic control module, which is part of a supplied device. In     some embodiments, each module provides power and control     instructions to one sensor in the array, which is located on a     device arm. Setup 1600 in an exemplary embodiment, appears as shown     in FIG. 16 . -   As shown in FIG. 16 , an individual lies in a supine position on a     base unit (such as a bed) 1607. The sensor array 1606 is positioned     adjacent to a location on the subject, such as adjacent to a chest     position, by adjusting an arm 1605 of a mobile cart device. A shield     1603 is positioned between (i) the subject and sensor array 1606     and (ii) one or more additional devices 1601 such as an electrical     device, a power supply, a computer, or any combination thereof. One     or more subcomponents 1602 (such as wiring) that are needed to     operatively connect the one or more additional devices and the     sensor array 1606 is housed in a tubing or a covering. An opening     1604 in the shield 1603 is configured to accept the one or more     subcomponents 1602 to pass there through. -   As shown in FIG. 17 , a shield 1700, in some embodiments, comprises     more than one layer, such as a first layer 1701 and a second layer     1702. In some embodiments, the first layer 1701 and second layer     1702 are adjacent to one another. In some embodiments, the first     layer 1701 and second layer 1702 are separated by a spacing -   A base unit: (such as a patient bed), in some embodiments, is     positioned within a magnetically shielded environment upon which an     individual is positioned (such as lying supine) prior to device use.     This bed is constructed of non-ferromagnetic materials (such as     entirely constructed of non-ferromagnetic materials) and     non-permanent magnets in order to minimize the amount of     interference the device may read.

Setup: To setup a device for use, one or more of the following exemplary steps are carried out:

-   Ensure that device frame and sensor housing are located inside a     magnetically shielded room. Keep a device in storage mode with a     device’s arm collapsed. -   Ensure that the control units are connected to a sensor housing and     a device frame through one or more portals of the magnetically     shielded room. -   Power on the computer interface and launch the software application     (such as Maxwell). -   Power on an Electronic Control Module. -   Position an individual on a base unit 1704 (i.e. bed) with the     individual’s head aligned with one side of the base unit 1704 and     the individual’s feet aligned towards a second side of the base unit     1704, such as shown in FIG. 17 . A magnetically shielded room has     enough clearance to position a magnetocardiograph along at least one     side of the base unit 1704. -   An individual is positioned on a base unit 1704 that is configured     such that at least a portion of the base unit 1704 is slidable into     and out of a shield opening. The base unit 1704 is configured to     slide on a track 1705 or may slide on one or more rollers or wheels.     As least a portion of subcomponents 1703, such as a wiring, is     configured to operatively connect the sensor array to one or more     other devices, is configured to enter at least a portion of the     shield 1700. Subcomponents 1703 are associated with a hook or latch     or track structure within the shield 1700. -   Extend an arm of the frame such that the arm makes about a 90 degree     angle with a vertical portion of the frame with a handle (such as a     curved handle). -   Move the device towards the subject by pulling the handle on the     frame. Position the device such that the sensor housing is above an     area of interest on the subject (such as the chest area). Make small     adjustments such that the square platform is put in an optimal     position. -   Align the housing on the individual’s left side with the rightmost     side of a sensor array platform on or proximally above and parallel     to the individual’s center line. -   Use a lift mechanism at the end of the frame’s arm to adjust a     height of the sensor housing. The sensor housing is lowered to a     location where rests on or proximally above an area of interest on     the individual (e.g. chest). The handle is rotated in a first     direction in order to lower the sensor housing. The handle is     rotated in a second direction to raise the sensor housing.

Initiation: After a frame is in position, one or more sensors are activated to prepare for recording a signal, such as cardiac magnetic activity. To begin initiation, a user logs in to a software application (such as Maxwell) and selects the data acquisition module. If there is trouble with any of the steps below, the application is closed and attempts to reopen. If a problem does not go away, the computer interface is rebooted. To initiate a device for use, one or more of the following is adhered to:

-   Ensure connection to all sensors (such as 8 sensors) exists by     checking sensor status in the data acquisition software user     interface. -   Initiate the autostart procedure through the software application by     pressing “autostart” in the data acquisition software user     interfaces. This process calibrates one or more sensors for use.     Before continuing, ensure that the readiness indicator found in the     software UI has turned green and the status reads “ready”.

Recording: After initiation is complete, the device is ready to capture a signal, such as a cardiac magnetic field data. To begin, one or more of the following is carried out:

-   Select the “acquire” button in the software application. Selecting     this option plots the magnetic field collected from the sensors in a     viewing window found on the acquisition software UI. -   Ensure a collected magnetic field is characteristic of a signal,     such as a cardiac electrical activity. -   To save data to a file, select the “record” option. Select     preferences for period length of data acquisition, file name, and     file save location. Select “save” to begin saving to file.     Application, in some embodiments, automatically cease saving after a     selected amount of time that has elapsed. Files are named in     accordance with institutional policy to protect subject identifying     information.

Power-down and Storage: After device use is complete, the system is powered down by following one or more of the following:

-   Close the application on the computer. -   Power off the electronic control modules by turning the toggle     switch to the “off” position. -   Power off the computer.

Within the magnetically shielded enclosure a handle of the device is rotated in a first direction to raise a sensor platform. A device is repositioned by pulling a handle (such as a curved handle) so that the arm does not intersect with the subject or base unit (such as a bed). The extension arm is moved downward towards the ground to return the device to a storage mode. The subject is assisted in rising from the base unit. The user, the subject, or a combination thereof has the magnetically shielded enclosure.

Example 2

Setup: To setup a device for use, one or more of the following exemplary steps are carried out:

-   Ensure that a device frame and a sensor housing are free of defects     or damage. -   Power on a computer interface and launch a software application. -   Power on the Electronic Control Modules. -   Pull out a base unit (such as a bed) from the magnetic shielding     chamber until the bed is fully outside of the shielding chamber. -   Ensure locking components of the sensor array and arm (such as an     extension arm) are unlocked. Move the sensor array away from the     base unit so that the sensor array or portion thereof is not above     the base unit. -   Assist an individual onto a surface of the base unit. Position the     individual on the base unit with an individual’s head aligned     towards to opening of the bore and an individual’s feet aligned     towards the other, such as shown in FIG. 17 . -   Move the sensor array over an area of interest on the individual     (such as an individual’s chest). -   Make adjustments such that a sensor array platform is positioned     correctly. The housing is aligned on the subject’s left side, with     the rightmost side of the sensor array platform above and parallel     to the subject’s center line. -   Lower the sensor array platform to adjust height of the sensor     housing. Housing is lowered to a point where it may rest on or     proximally above a position of interest on the subject (e.g. chest). -   Lock pivots or joints or extension points of the sensor array to     restrict motion of the array. -   Slide the base unit into the recess opening of the shield until an     external light on the device is indicated (such as turned on, or     changed color such as turning green).

Initiation: After the frame is in position, one or more sensors are activated to prepare for recording a signal, such as a cardiac magnetic activity. To begin initiation, a logs in to a software application and selects the data acquisition module. If there is trouble with any of the steps below, the application is closed and attempts to reopen. If the problem does not go away, the computer interface is rebooted. To initiate a device for use, one or more of the following is carried out:

-   Ensure connection to one or more sensors (such as 8 sensors) exists     by checking sensor status in the data acquisition software user     interface. -   Initiate the autostart procedure through the software application by     pressing “autostart” in the data acquisition software user     interface. This process calibrates one or more sensors for use.     Before continuing, ensure that the readiness indicator found in the     software UI has turned green and the status reads “ready”.

Recording: After initiation is complete, the device is ready to capture a signal, such as a cardiac magnetic field data. To begin, one or more of the following is adhered to:

-   Select the “acquire” button in the software application. Selecting     this option plots the magnetic field collected from the sensors in a     viewing window found on the acquisition software UI. -   Ensure one or more collected magnetic field is characteristic of a     signal, such as a cardiac electrical activity. -   To save the data to file, select the “record” option. Select     preferences for period length of data acquisition, file name, and     file save location. Select “save” to begin saving to file.     Application automatically ceases saving after the selected amount of     time has elapsed. Files are named in accordance with institutional     policy to protect subject identifying information.

Power-down and Storage: After device use is complete, the system is powered down by following one or more of the following:

-   Close the application on the computer. -   Power off the electronic control modules by turning the toggle     switch to the “off” position. -   Power off the computer.

The base unit (such as a bed) is moved out of the magnetic shielding chamber. One or more joints or pivots or extensions or combinations thereof of the sensor array or arm is unlocked and is moved away from the base unit such that the path of motion is out of an individual’s way. The subject is assisted from leaving the base unit. One or more of the sensor arrays, sensor housing, an internal surface of a shield, a surface of a base unit, or any combination thereof is cleaned or sanitized between use of a first subject and a second subject.

Example 3

Setup: To setup device for use, one or more of the following exemplary steps is carried out:

-   Power on a computer interface and launch a software application. -   Power on an Electronic Control Modules -   Position an individual on a base unit (such as a standard hospital     bed) with an individual’s head aligned with one side of the base     unit and individual’s feet aligned towards a second side of the base     unit, such as shown in FIG. 17 . The room of operation having     sufficient clearance to position a sensor array (such as a     magnetocardiograph) along at least one side of the base unit. -   Extend a device’s arm and increase a height of the device by either     pulling up on the arm or using the “raise/lower” button on a sensor     array so that the sensor array is positioned above an individual. -   Move the device towards the individual by pushing the mobile cart.     Position the device such that the sensor housing is above the     subject (such as above the subject’s chest). -   Use a lift mechanism at an end of a frame’s arm to adjust a height     of the sensor housing. A sensor housing is lowered to the position     where it rests on or proximally above the position (such as an     individual’s chest) at the point of normal subject inhalation. -   Make adjustments such that the sensor array platform is positioned     correctly. The housing is aligned on the subject’s left side, with     the rightmost side of the sensor array platform above and parallel     to the subject’s center line.

Initiation: After the frame is in a position, one or more sensors are activated to prepare for recording a signal, such as a cardiac magnetic activity. To begin initiation, a user logs in to a software application and selects the data acquisition module. If there is trouble with any of the steps below, the application is closed and is attempted to reopen. If the problem does not go away, the computer interface is rebooted. To initiate a device for use, one or more of the following is carried out:

-   Ensure connection to one or more sensors (such as 8 sensors) exists     by checking sensor status in the data acquisition software user     interface. -   Initiate the autostart procedure through the software application by     pressing “autostart” in the data acquisition software user     interfaces. This process calibrates one or more sensors for use.     Before continuing, ensure that the readiness indicator found in the     software UI has turned green and the status reads “ready”.

Recording: After initiation is complete, the device is ready to capture a signal, such as a cardiac magnetic field data. To begin, one or more of the following is carried out:

-   Select the “acquire” button in the software application. Selecting     this option plots the magnetic field collected from the sensors in a     viewing window found on the acquisition software UI -   Ensure one or more collected magnetic fields are characteristic of a     signal, such as a cardiac electrical activity. -   To save the data to file, select the “record” option. Select     preferences for period length of data acquisition, file name, and     file save location. Select “save” to begin saving to file.     Application automatically ceases saving after the selected amount of     time has elapsed. Files are named in accordance with institutional     policy to protect subject identifying information.

Power-down and Storage: After device use is complete, the system is powered down by following one or more of the following:

-   Close the application on the computer. -   Power off the electronic control modules by turning the toggle     switch to the “off” position. -   Power off the computer.

The device’s arm is raised by pushing up on the arm or using a “raise/lower” button on the sensor array so that the sensor array is above the subject’s chest level. The subject is assisted in rising from the base unit.

Example 4

FIG. 18 shows an example of an embodiment of a shield comprising three layers of mu-metal (three innermost layers) and one layer of aluminum alloy (outer layer). The truncated end to the left and the open end to the right. Although one end of the shielding cylinder is completely open, if the sensor assembly is located far enough from this open end, the EM noise entering the shield bore through the open end will decay to a level low enough so as not to affect the accuracy of any magnetic fields measurements taken from an individual positioned within the shield.

FIG. 19 shows a plot of magnetic field measurements along the centerline of a shield such as the one shown in FIG. 18 . Field levels less than 50 nT are acceptable for system operation. The decay of ambient noise has been measured and is shown in FIG. 19 . Since the head of a patient will be positioned roughly at the point where the cylinder begins to taper, the location of, for example, an organ of interest such as, for example, the heart of an individual, within the EM shield can be expected to lie comfortably within a level of background noise (< 50 nT) deemed acceptable for reliable device performance.

Example 5

FIG. 20 shows an example of a sensor array (sensors shown in black, cables cut for clarity). For precise positioning of this sensor array above the patient’s heart, the housing can be raised, lowered and translated in a transverse direction (shoulder to shoulder) via a manually operated gear mechanism.

FIG. 21 shows an example of a 3D rendering of a sensor head cage mounted on a bed of a shield such as the shield of FIG. 18 (the patient’s head would be on the left, chest underneath the arch within the shield).

Example 6

Using systems, devices, and methods of the present disclosure, a magnetocardiographic (MCG) device (Genetesis, Inc, Mason OH) was used in the assessment of a potential acute coronary syndrome population admitted for observation care following normal sequential troponin and electrocardiographic (ECG) assessments. The data demonstrated a 33% sensitivity, 78% specificity, 13% positive predictive value (PPV), and 92% negative predictive value (NPV) when compared to cardiac stress test guided coronary arteriography, where a positive result was defined as at least one stenosis of an epicardial coronary artery at a degree of greater than 50%. These results were obtained based upon the use of non-parametric qualitative interpretation (NPQI) rules which were taught to the investigators who interpreted the magnetic field maps. The data were consistent with the diagnostic accuracy of MCG reported using similar patient populations with respect to sensitivity (73% to 98%) and specificity (41% to 95%). Importantly, ischemic diagnostic patterns on MCG appear to be similar and to be highly sensitive to both acute and subacute levels of cardiac ischemia in these various reports, despite a very diverse set of interpretation rules for the various devices (as shown in Table 1). In fact, many studies of MCG may focus on patients with ischemic MCG patterns in the absence of traditional diagnostic modalities being negative.

TABLE 1 Interpretation Rules for MCG Devices Author Interpretation Rule Hailer Evaluates the current density vector map. A non ischemic map: the main current vectors are located in the center or left part of the map and directed within a 10° to 80° sector; the pattern is dipolar and the vortices are equal (Category 0, 1, or 2). An ischemic map: the pattern is non dipolar and the main current vectors are located in the upper part of the map and directed within a 2 20° to 110° sector (Category 3 or 4). Park Assessed magnetic field maps. Criteria for ischemia were exclusively analyzed during the time interval between the beginning of the T wave (Tbeg) and the maximum of the T wave (Tmax). Four parameters were defined, from which at least one parameter had to be abnormal for the MCG to be considered abnormal: the direction of the vector (from plus pole to minus pole), the change in the angle of this vector, the change in the distance between plus and minus poles, and the change in the ratio of the pole strengths. Rapid changes in these parameters in a time interval of 30 ms in the MCG interval between Tbeg and Tmax were characteristic of ischemic disease. Kyoon Assessed maximum current angle, distance of poles in current density vector (CDV), field map angle in magnetic field maps and determined only electromagnetic dipole vs non-electromagnetic dipole patterns in T-peak which had significant correlation with myocardial ischemia. A electromagnetic dipole pattern was defined as a magnetic field containing two poles. If there were more than 2 poles, it was defined as a non-electromagnetic dipole pattern. Grapeuluk Assessed the Kullback-Leibler (KL) entropy, normalized residual magnetic field strength and deviations in the magnetic field map orientation. The mean values of these parameters during the depolarization and repolarization were used for further classification with the help of logistic regression. The feature set based on the KL-entropy demonstrated the best classification results (sensitivity/specificity of 85/80%), followed by the residual feature (85/75%) and the magnetic field orientation feature (80/73%) sets. The forward stepwise technique was applied to select the best set of features from the combined feature set. Two parameters were selected, namely the KL-entropy for the repolarization period and the residual parameter for the depolarization period. Tolstrup Assessed the effective magnetic electromagnetic dipole vector (EMDV) analysis, which is based on an automated analysis of the ventricular repolarization. From the averaged data the software compares all T-waves simultaneously and calculates the difference between the most positive and most negative magnetic signal at each time point during cardiac repolarization. Steinberg Assessed the period of repolarization from the early part of the T wave to the T-wave peak (“ischemia analysis window”). The angle α between the positive (+) pole and the negative (-) pole is determined. The following four criteria are considered as normal boundaries for these parameters of the magnetocardiogram, over the analysis window: 1. The angle is -110° ≤ α ≤ 20°. 2. The angle α between the positive (+) pole and the negative (-) pole rotates by less than 45° in 30 ms. 3. The distance between the positive (+) pole and the positive (-) pole varies by less than 20 mm in 30 ms. 4. The ratio between the field strength of the positive (+) pole and the field strength of the negative (-) pole varies by less than 0.3 in 30 ms. Kandori Assessed the current distribution parameters (CDPs) and developed parameters using the have been developed based maximum current vector; the maximum amplitude of Total Current Vector; and area ratio of abnormal current vector. Criteria are defined for ischemia.

MCG represents a noninvasive technique that comprises measuring and recording cardiac magnetic fields generated by the electrical currents which result from the cardiac myocyte processes of depolarization and repolarization. Although various detectors have been used during the development of MCG devices, the final output uses measurements of the cardiac magnetic field simultaneously at multiple points to generate magnetic field maps which can be analyzed as indicators of normal and abnormal cardiac physiology. Although ECG uses voltage assessment of cardiac electrical function, the MCG appears uniquely sensitive to both tangential and vortex currents which arise in the subepicardial and deeper myocardial layers due to the gradients in the electrical properties between those of normal tissue and those of ischemic tissue, which is due in part to such currents not having an electrical counterpart.

These results were obtained based upon the use of a non-parametric qualitative interpretation (NPQI) rules which were taught to the investigators who interpreted the magnetic field maps. Because of the unique potential advantages of MCG and the variability in MCG interpretation, magnetic field maps were re-assessed to develop parameter-based interpretation (PBI) rules for an MCG generated using systems, devices, and methods of the present disclosure, for patients with cardiac ischemia and patients without cardiac ischemia, based on the actual clinical outcomes. Additionally, accuracy statistics were compared between the study readers, an experienced MCG interpreter, and Delphi process derived parameter-based interpretation rules were determined, along with an inter-rater reliability rating.

Methods

The MCG study was performed as follows. Briefly, 101 potential acute coronary syndrome patients were admitted for observation evaluation following a serial troponins and ECGs negative for acute myocardial infarction. There were 4 patients taken directly to coronary angiography on clinical grounds, while the remaining 97 patients underwent cardiac stress tests, with positive patients being further allocated to coronary angiography with or without revascularization at the discretion of the treating cardiologist. The results of the magnetic field maps as assessed by the investigators (study read) using the NPQI methodology based on their pre-trial training were retrieved. A blinded interpretation (over read) of the magnetic field maps was performed by an experienced individual using the same NPQI methodology. A Delphi process was performed by a separate group of individuals using three rounds of reviews of the magnetic field maps compared to the actual outcomes to develop the criteria for the PBI rules outlined below.

The three sets of interpretations (study, over read, and PBI) were compared for sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, PPV, NPV, and accuracy. Cohen Kappa scores were calculated for PBI versus each of the other two sets of interpretation. Magnetic field interpretations were defined as non-ischemic or ischemic using the rules described below. Clinical ischemia was redefined using the decision to perform a coronary angiographic determined revascularization as a composite assessment of an epicardial coronary arterial lesion associated with cardiac ischemia. No patient had a troponin level or ECG diagnostic for cardiac ischemia.

The non-parametric qualitative interpretation (NPQI) rules have been based on the following outputs obtained by the various MCG devices: a magnetic field map, which is generated presented to the interpreting physician as a set of 36 superimposed waveforms of magnetic field intensity versus time for a single cardiac cycle (as shown in FIG. 33 ). The magnetic field map is evaluated for interpretation (instead of, or in conjunction with, analysis of the waveform). The magnetic field map represents a 2-dimensional (2D) representation of the sum of the current vectors. Each individual waveform represents the magnitude of the magnetic field normal to the chest wall measured at a distance of several inches above the torso of an individual. The MCG imaging and analysis system was used to acquire data from 36 sensors arranged in a uniform 6 x 6 grid, so each dark circle shown in the map below represents a “true data point”, color coded to represent direction of magnetic field and its intensity. For example, red colors denote current vectors with positive magnitudes, while blue colors denote current vectors with negative magnitudes. All information represented by the “sea of color” in the magnetic field map (MFM) external to the 36 grid points is interpolated using data from these grid points (as shown in FIG. 33 ). For example, interpolation may be performed to up-sample the image from a 6 x 6 grid of pixels to a 50 x 50 grid of pixels. The magnetic field may be rendered as a visual representation of the sensed magnetic field data in both a wave form pattern (as shown in FIG. 34 ), which mimics the traditional format of the voltage presentation of an ECG, and/or a separate magnetic field map demonstrating normal or ischemic patterns. For example, the wave form pattern may comprise the superimposition of data acquired over multiple (e.g., 1,000) discrete time points of a single cardiac cycle. For each of the discrete time points, the most positive and negative values of the MCG data may be determined and used for further analysis. For example, the wave form pattern may include an R-peak depolarization time 3402 and a T-peak re-polarization time 3404 (as shown in FIG. 34 ).

Non-Parametric Qualitative Interpretation (NPQI)

The magnetic field maps may be subjected to non-parametric qualitative interpretation (NPQI) rules as follows. First, an assessment of the quality of scan is performed to evaluate the readability of the scan. Second, the MCG waveform is examined in order to identify the P wave deflection (which may be a small deflection), the QRS complex deflection, and the T wave deflections. Available time intervals on the horizontal baseline can be used to measure PR, QRS, and QT intervals, as appropriate. The reader may specifically observe for evidence of interval prolongation (e.g., QRS interval for evidence of bundle branch block/conduction delay), which may be indicative of conduction disease, which may impact interpretation.

Third, an assessment of the interval between the onset of T wave deflection and the peak of the T wave is performed, as follows. During this T wave interval, the reader evaluates whether the magnetic pole cores (e.g., red over blue electromagnetic dipoles) are well demarcated. For example, poorly defined magnetic pole cores are indicative of an abnormality in myocardial electrical function (e.g., characteristic of cardiac ischemia in the individual). Further, the vector angle stability is determined between the positive magnetic pole core and the negative magnetic pole core. For example, a vector angle stability of less than 30 degrees is indicative of a normal finding; conversely, a mobile or rotating vector angle through the T wave interval is indicative of an abnormal finding. Further, any significant gaps (e.g., areas with no net influx or outflux of magnetic force) in magnetic field distribution are identified. For example, any asymmetric gaps in the cardiac magnetic field map are indicative of myocardial injury (e.g., characteristic of cardiac ischemia in the individual). Further, magnetic pole splitting is assessed. For example, the presence of distinct positive and negative magnetic poles during repolarization are indicative of a normal finding; conversely, a splitting of either the positive magnetic pole or the negative magnetic pole during this interval is indicative of an abnormal finding.

Fourth, diagnostic conclusions are determined using the NPQI rules as follows. A non-ischemic result (e.g., normal outcome) is assigned based on a combination of: a presence of well-defined magnetic cores during the T wave, a vector angle stability between the positive and negative magnetic pole cores of less than 30 degrees; and the presence of distinct positive and negative magnetic poles during repolarization. Conversely, an ischemic result (e.g., abnormal outcome) is assigned based on any one of the following: a presence of poorly defined magnetic pole cores, which is indicative of an abnormality in myocardial electrical function; a vector angle of at least 30 degrees, or a mobile or rotating vector angle through the T wave interval; the presence of asymmetric gaps in the cardiac magnetic field map; and a splitting of either the positive electromagnetic dipole or the negative electromagnetic dipole.

Parametric Based Interpretation (PBI)

Using systems, devices, and methods of the present disclosure, the magnetic field maps may be subjected to parametric based interpretation (PBI) rules as follows. First, an assessment of the quality of scan is performed to evaluate the readability of the scan. Second, an assessment of the duration of the QRS complex is performed for identification of a bundle branch block (e.g., having a duration greater than 120 milliseconds (ms)). This allows for the identification of the initial R peak (as the two are visualized with a bundle branch block), which may be used to calculate the angles as described below. Third, the peaks of both the R wave and the T wave are determined.

Third, the peaks of the R wave and the T wave were then used to calculate the respective R angle and T angle as follows. First, the center of a negative electromagnetic dipole (shown in blue) and the center of a positive electromagnetic dipole (shown in red) are identified on the magnetic field map corresponding to the R wave (FIG. 27A) and the T wave (FIG. 27B), respectively. For example, the center of the negative or positive electromagnetic dipoles may be identified by determining a centroid. the Next, using the center of the negative electromagnetic dipole (blue), an X vector is defined which extends horizontally to the right of the magnetic field map, and a Y vector is defined which extends from the center of the negative electromagnetic dipole (blue) through the center of the positive electromagnetic dipole (red).

Next, the peak R-depolarization angle is determined, which comprises determining an angle from the X vector to the Y vector for the R wave. A negative angle for the R wave is assigned when the Y vector was located counterclockwise relative to the X vector; conversely, a positive angle for the R wave is defined by when the Y vector was located clockwise relative to the horizontal X vector.

Similarly, the peak T-repolarization angle is determined, which comprises determining an angle from the X vector to the Y vector for the T wave. A negative angle for the T wave is assigned when the Y vector was located counterclockwise relative to the X vector; conversely, a positive angle for the T wave is defined by when the Y vector was located clockwise relative to the horizontal X vector.

Next, the RT peak angle difference is determined, which comprises determining the absolute difference between the two angles (the peak R-depolarization angle and the peak T-repolarization angle). For example, if the R peak angle is -45 degrees, and the T peak angle is -30 degrees, then the RT peak angle difference is 15 degrees.

Fourth, assessment of the entire T wave duration is performed for identification of a single electromagnetic dipole versus multiple electromagnetic dipoles (positive or negative) appearing during the course of the T wave on the magnetic field map.

Fifth, diagnostic conclusions are determined using the PBI rules as follows. A non-ischemic result is assigned when the RT peak angle difference is less than 100 degrees, or alternatively when the RT peak angle difference is between 170 degrees to 190 degrees and there is a single electromagnetic dipole present in the magnetic field map. An ischemic result is assigned when the RT peak angle difference is between 100 degrees to 170 degrees (with or without multiple electromagnetic dipoles present in the magnetic field map), or alternatively when there are multiple electromagnetic dipoles present in the magnetic field map (regardless of the value of RT peak angle difference).

Statistical analysis consisted of the calculation of sensitivity, specificity, positive and negative likelihood ratios, PPV, NPV, and accuracy. Cohen Kappa scores were calculated for PBI vs each of the other two sets of interpretation.

Results

The demographic and original outcome data, as reported in the Pena study, were obtained. The accuracy metrics and Kappa scores were calculated against the composite ischemia measure of coronary angiographic guided revascularization for the three reader groups, as shown in Table 2. The results demonstrated that assessment using the PBI rules generally out-performed assessment using the other two sets of interpretations, particularly with respect to NPV and overall accuracy, which are important when considering a “rule out” diagnostic test for cardiac ischemia. The Kappa scores were 0.82 for PBI vs Over Read, and 0.72 for PBI vs Study Read. These scores are both consistent with high correlation, suggesting that overall the MCG imaging and analysis device of the present disclosure may be used to produce high-quality magnetic field maps with consistently identifiable elements, which may be used to differentiate ischemia from non-ischemia. However, the incremental improvement in accuracy favoring the experienced reader over the study readers suggests a steeper learning curve. The superior accuracy of the PBI rules which are discrete may provide greater consistency and a shallower learning curve.

TABLE 2 Accuracy Metrics for PBI, NPQI (Over Read), and NPQI (Study Read) Sensitivity Specificity Positive Likelihood Ratio Negative Likelihood Ratio PBI 100% 73% 14.14 0 NPQI (Over Read) 100% 82% 5.56 0 NPQI (Study Read) 50% 79% 2.39 0.63 PBI 42% 100% 93% NPQI (Over Read) 18% 100% 83% NPQI (Study Read) 14% 96% 77%

Discussion

The data demonstrate that a straightforward structured set of PBI rules can provide an accurate interpretation of a cardiac magnetic field map for the purpose of diagnosing or excluding cardiac myocyte ischemia in individuals. The key elements that appear consistent for effective analysis of magnetic field maps are interrogation of both depolarization and the T wave dominated repolarization phases of cardiac cell function. These data are consistent with studies examining the diagnostic patterns resulting from ischemic alterations in current vectors and therefore the resulting magnetic field. Other studies may rely on varying interpretation rules, and many of the rule sets are relatively subjective in nature which makes consistent evaluation across providers more difficult to implement (as shown in Table 1). The present study provides a narrower set of magnetic field map data necessary to diagnose ischemia, much of which may be understood visually, but is also determined precisely using mathematical algorithms. The set of rules presented focus on comparing depolarization, which is non-energy dependent and represented by the peak of the R wave, which is provided automatically to the reader by the software analysis and assessment of the magnetic field wave forms. Alternatively, the reader can override this displayed data element (which has been determined using mathematical algorithms) and manually select his or her own determination of the location of the peak R wave (which has been determined based on the reader’s visual determination), which is then used to define the “Peak R” and subsequently the “R angle” (as described above). The reader then turns to the peak T wave, which has been provided automatically to the reader by the software analysis and assessment of the magnetic field wave forms. Alternatively, the reader can override this displayed data element (which has been determined using mathematical algorithms) and manually select his or her own determination of the location of the peak T wave (which has been determined based on the reader’s visual determination), which is then used to define the “Peak T” and subsequently the “T angle” (as described above). The difference between these angles is defined as the “R-T angle difference”. These metrics are important because cardiac cell depolarization begins at the endocardial surface and proceeds to the epicardial surface, only to have repolarization proceed in the opposite direction. Therefore, although theoretically the gap should be zero, the data indicate that a physiologically non-ischemic pattern can range from 0 degrees to 100 degrees. It should be noted that a left bundle branch block produces a double R peak phenomenon, and by convention, the initial peak was selected for determination of the “R-T angle difference”, with normal defined in the same fashion. Alternatively, conduction abnormalities have been identified by MCG, which are not identified on ECG, which produce but assessment of the MFM demonstrated that an “R-T angle difference of 180 degrees ± 10 degrees.

The other important criteria identified in the analysis which is clearly associated with cardiac ischemia is the appearance of multiple electromagnetic dipoles (positive or negative) during the course of the T wave. In fact, this was determined to be almost universally associated with cellular level ischemia regardless of etiology, as it was observed in association with poorly controlled heart failure and epicardial coronary arterial disease. This phenomena was also suggested in the work of Hailer et al. Abnormal MCG patterns appear to persist early in the recovery phase following both ST elevation and non-ST elevation myocardial infarction, and are associated with higher morbidity and mortality. This suggests that persistent microvascular ischemia represents a current unmet need to guide post discharge medical management in cardiac patients. Similarly, because the ischemic magnetic field map diagnostic patterns represent cellular level ischemia, regardless of the device used, the technology potentially broadens the patient populations beyond simply those at risk for significant epicardial coronary arterial occlusive disease.

The accuracy statistics may be confirmed in different groups of patients at risk for ischemic cardiac myocytes, including STEMI, NSTEMI, microvascular ischemia, and Type 2 myocardial infarction. The ability to develop a diagnostic pathway that includes MCG to inform the early evaluation of potential acute coronary syndrome patients with indeterminate troponins is another useful role for assessing magnetic flow maps. Further, systems, devices, and methods of the present disclosure may be used to supplant other methods of assessing cardiac stress patients without the need for highly trained technologists or radiopharmaceuticals.

Conclusion

Using systems, devices, and methods of the present disclosure, magnetocardiograph imaging and analysis devices were shown to be capable of producing magnetic field maps which can be evaluated using a structure PBI rule set to efficiently diagnose cardiac ischemia resulting from multiple mechanisms without the need for highly trained technologists, radiopharmaceuticals, or exposure to external beam radiation. Further validation of specific diagnostic criteria related to the assessment of both the QRS complex and T wave may be performed with broader use of the technology across various patient populations. Therefore, the systems, devices, and methods of the present disclosure enable the rapid and safe assessment of cardiac patients without the need for expensive shielded rooms closer to the point of service based upon assessment of cardiac magnetic field maps.

References

[Pena ME, Pearson CL, Goulet MP, Kazan VM, DeRita AL, Szpunar SM, Dunne RB. A 90-second magnetocardiogram using a novel analysis system to assess for coronary artery stenosis in Emergency department observation unit chest pain patients Int J Cardiol Heart Vasc. 2020 Jan 8;26:100466. doi: 10.1016/j.ijcha.2019.100466. eCollection 2020 Feb.] is incorporated by reference herein in its entirety.

[Hailer B, Van Leeuwen P. Detection of coronary artery disease with MCG. Neurol Clin Neurophysiol 2004;2004:82] is incorporated by reference herein in its entirety.

[Park JW, Leithauser B, Vrsansky M, et al. Dobutamine stress magnetocardiography for the detection of significant coronary artery stenoses - a prospective study in comparison with simultaneous 12-lead electrocardiography. Clin Hemorheol Microcirc. 2008;39(1-4):21-32. 4] is incorporated by reference herein in its entirety.

[Lim HK, Kwon H, Chung N, Ko YG, Kim JM, Kim IS, Park YK. Usefulness of magnetocardiogram to detect unstable angina pectoris and non-ST elevation myocardial infarction. Am J Cardiol. 2009 Feb 15;103(4):448-54] is incorporated by reference herein in its entirety.

[Gapelyuk A, Schirdewan A, Fischer R, et al. Cardiac magnetic field mapping quantified by kullback-leibler entropy detects patients with coronary artery disease. PhysiolMeas. 2010;31(10): 1345-1354] is incorporated by reference herein in its entirety.

[Tolstrup K, Madsen BE, Ruiz JA, et al. Non-invasive resting magnetocardiographic imaging for the rapid detection of ischemia in subjects presenting with chest pain. Cardiology. 2006;106(4):270-276] is incorporated by reference herein in its entirety.

[Steinberg BA, Roguin A, Watkins SP 3rd, et al. Magnetocardiogram recordings in a nonshielded environment- reproducibility and ischemia detection. Ann Noninvasive Electrocardiol. 2005;10(2):152-160] is incorporated by reference herein in its entirety.

[Kandori A, Ogata K, Miyashita T, et al. Subtraction magnetocardiogram for detecting coronary heart disease. Ann Noninvasive Electrocardiol. 2010;15(4):360-368] is incorporated by reference herein in its entirety.

[Baule G, Mcfee R. Detection of the magnetic field of the heart. Am Heart J. 1963;66:95-96. 8] is incorporated by reference herein in its entirety.

[Moshage W, Achenbach S, Weikl A, et al. Clinical magnetocardiography: Experience with a biomagnetic multichannel system. Int J Card Imaging. 1991;7(3-4):217-223] is incorporated by reference herein in its entirety.

[Hopenfeld B, Stinstra JG, Macleod RS. Mechanism for ST depression associated with contiguous subendocardial ischemia. J Cardiovasc Electrophysiol. 2004;15(10):1200- 1206] is incorporated by reference herein in its entirety.

[Lim HK, Kwon H, Chung N, Ko YG, Kim JM, Kim IS, et al. Usefulness of magnetocardiogram to detect unstable angina pectoris and non-ST elevation myocardial infarction. Am J Cardiol 2009;103: 448-54] is incorporated by reference herein in its entirety.

[Kyoon Lim H, Kim K, Lee YH, Chung N. Detection of non-ST-elevation myocardial infarction using magnetocardiogram: new information from spatiotemporal electrical activation map. Ann Med. 2009;41(7):533-46] is incorporated by reference herein in its entirety.

[Van Leeuwen P, Hailer B, Beck A, Eiling G, Grönemeyer D. Changes in dipolar structure of cardiac magnetic field maps after ST elevation myocardial infarction. Ann Noninvasive Electrocardiol 2011; 16:379-87] is incorporated by reference herein in its entirety.

Example 7

Using systems, devices, and methods of the present disclosure, a magnetocardiographic (MCG) device (Genetesis, Inc, Mason OH) was used in the assessment of a potential acute coronary syndrome population admitted for observation care following normal sequential troponin and electrocardiographic (ECG) assessments. Magnetic field maps were generated using the MCG device and were interpreted using PBI rules, as described herein.

The interpretation of magnetic field maps may comprise pattern recognition of the magnetic field maps. For example, an initial focus of the interpretation may be the R-peak and the duration of the T-wave. In some embodiments, the interpretation of magnetic field maps comprises viewing the magnetic field maps both in time series and freezing images during waveform segments of interest (e.g., corresponding to R-peak and T-peak time periods). This approach provides both global and granular data within the MCG pattern, and enables static and dynamic view of the magnetic electromagnetic dipoles in the magnetic field maps.

The interpretation of magnetic field maps may comprise identifying positive magnetic poles (e.g., shown in red) and negative magnetic poles (e.g., shown in blue) during the R-peak and duration of the T-wave. For example, the positive magnetic pole may be determined as the center (e.g., centroid) of the positive magnetic field values, while the negative magnetic pole may be determined as the center (e.g., centroid) of the negative magnetic field values. A first vector may be defined between the positive magnetic pole and the negative magnetic pole, for purposes of determining an angle therefrom. Alternatively, a first line, a line segment, or a ray may be defined between the positive magnetic pole and the negative magnetic pole, for purposes of determining an angle therefrom. A second vector may be defined as a horizontal vector (e.g., having the same direction as the positive x-axis), for purposes of determining an angle therefrom. Alternatively, a second line, a line segment, or a ray may be defined that is parallel to a horizontal vector (e.g., having the same direction as the positive x-axis), for purposes of determining an angle therefrom. Without loss of generality, the second vector, line, line segment, or ray may pass through the negative magnetic pole (shown in blue). Alternatively, the second vector, line, line segment, or ray may pass through another point (e.g., any point between the positive and negative magnetic poles) without affecting the determination of the angle therefrom. The first vector and/or the second vector may be expressed using any suitable coordinate system, including but not limited to, a 2-D Cartesian coordinate, a 3-D Cartesian coordinate system, a rectangular coordinate system, a parametric coordinate system, and a polar coordinate system.

After determining the first vector and the second vector, a vector angle may be defined based on the positive and negative magnetic poles at a given time. The vector angle may represent an angle between the first vector and the second vector. The vector angle may be determined as the smallest angle change between the first vector and the second vector. For example, the vector angle may have a value ranging from 0 to 360 degrees, or equivalently may have any integer multiple of 360 added or subtracted therefrom to arrive at a value ranging from 0 to 360 degrees. As an example, the vector angle θ may be determined using the following expression: cos(θ) = a • b / (|a| |b|), where a and b denote the first vector and the second vector, respectively, “•” denotes a vector dot product, and “| |” denotes a vector magnitude.

As an example, the peak R-depolarization angle may be determined as the vector angle of a magnetic field map associated with the period of time that the R-wave (and corresponding R-peak) occurs (e.g., which may be measured using an ECG). As another example, the peak T-repolarization angle may be determined as the vector angle of a magnetic field map associated with the period of time that the T-wave (and corresponding T-peak) occurs (e.g., which may be measured using an ECG).

Such a vector angle may be determined at two different time points (e.g., during the R-peak and during the T-peak), and the difference, change, or mobility in the vector angle of two different magnetic field maps (e.g., from the R-peak as compared to the T-peak) may be used to perform the magnetic field map assessment of coronary artery disease (e.g., a positive or negative result for ischemia). The difference, change, or mobility in the vector angle may be determined based on the positive clockwise angle between the two vector angles (e.g., from the R-peak as compared to the T-peak). Alternatively, the difference, change, or mobility in the vector angle may be determined based on the positive counterclockwise angle between the two vector angles (e.g., from the R-peak as compared to the T-peak).

As an example, the presence of a mobile or rotating vector angle with a difference of no more than 100 degrees is indicative of the magnetic field maps showing no evidence of ischemia (e.g., a negative or non-ischemic result). Conversely, as another example, the presence of a mobile or rotating vector angle with a difference of more than 100 degrees is indicative of the magnetic field maps showing evidence of ischemia (e.g., a positive or ischemic result).

As another example, the presence of a complete 180-degree flip of the vector angle difference between the positive and negative magnetic poles (e.g., comparing the R-peak magnetic field map to the T-peak magnetic field map) is indicative of the magnetic field maps showing a conduction abnormality, not ischemia, in the heart of the subject; the subject receives a positive result for an abnormality but a negative result for ischemia. As another example, the presence of multiple electromagnetic dipoles in the magnetic field map appearing during any portion of the T-wave is indicative of the magnetic field maps showing an abnormal finding.

The magnetic field maps associated with normal outcomes (e.g., no detected cardiac abnormalities in the subject) may have one or more of the following characteristics. First, a normal QRS duration and morphology may be present, without evidence of any waveform variants that may be indicative of potential abnormalities. Second, a vector difference between electromagnetic dipoles of the magnetic field maps at R-peak and T-peak is 100 degrees or less. The positive pole is usually located near the right upper quadrant (RUQ) of the viewing screen, while the negative pole is usually located near the left lower quadrant (LLQ) of the viewing screen, when viewing the pole orientation in the magnetic field image during T wave phase. As an example, a complete 180-degree flip of the vector angle difference between the R-peak and the T-peak is indicative of no evidence of ischemia (e.g., a negative or non-ischemic result). Third, only one positive electromagnetic dipole and one negative electromagnetic dipole may be present during T-wave duration.

FIGS. 35A-35B show an example of R-peak and T-peak magnetic field maps, respectively, of a subject, which are interpreted to have a normal (e.g., non-ischemic) result, where the vector between the positive and negative electromagnetic dipoles during the R-peak and as compared to the T-peak are consistent. Here, the R-peak occurs at a time of 400 ms on the waveform representation (FIG. 35A) corresponding to peak R-depolarization, while the T-peak occurs at a time of 703 ms on the waveform representation (FIG. 35B) corresponding to peak T-repolarization.

FIGS. 36A-36B show an example of R-peak and T-peak magnetic field maps, respectively, of a subject, which are interpreted to have a normal (e.g., non-ischemic) result, where the vector between the positive and negative electromagnetic dipoles during the R-peak as compared to T-peak show a 180-degree flip. Here, the R-peak occurs at a time of 400 ms on the waveform representation (FIG. 36A) corresponding to peak R-depolarization, while the T-peak occurs at a time of 717 ms on the waveform representation (FIG. 36B) corresponding to peak T-repolarization.

Further, the magnetic field maps associated with abnormal outcomes (e.g., detected cardiac abnormalities in the subject, such as an ischemic or a conduction abnormality) may have one or more of the following characteristics. First, multiple poles are present in the magnetic field map during the T wave segment. Second, the positive and negative magnetic poles of the magnetic field maps are rotating around each other more than 100 degrees, when comparing the R-peak magnetic field map to the T-peak magnetic field map.

FIGS. 37A-37B show an example of R-peak and T-peak magnetic field maps, respectively, of a subject, which are interpreted to have an abnormal (e.g., ischemic) result, where during the T-peak magnetic field map, multiple electromagnetic dipoles are present, which are completely surrounding the positive electromagnetic dipole. Here, the R-peak occurs at a time of 399 ms on the waveform representation (FIG. 37A) corresponding to peak R-depolarization, while the T-peak occurs at a time of 609 ms on the waveform representation (FIG. 37B) corresponding to peak T-repolarization.

FIGS. 38A-38B show an example of R-peak and T-peak magnetic field maps, respectively, of a subject, which are interpreted to have an abnormal (e.g., ischemic) result, where the vector between the positive and negative electromagnetic dipoles during the R-peak as compared to T-peak show a electromagnetic dipole movement of more than 100 degrees. Here, the R-peak occurs at a time of 400 ms on the waveform representation (FIG. 38A) corresponding to peak R-depolarization, while the T-peak occurs at a time of 690 ms on the waveform representation (FIG. 38B) corresponding to peak T-repolarization.

Example 8

Using systems, devices, and methods of the present disclosure, a set of one or more of the following parameters and/or plots are determined using magnetic field maps of an individual, and the set of parameters and/or plots are analyzed to assess cardiac ischemia in the individual. Parameters may be quantitatively measured for parametric classification (e.g., using dipole parameters, integrated MCD parameters, integrated ECD parameters, mean PCD parameters, isointegral parameters, field map correlation parameters, R_peak pegged dipole parameters, pseudo current arrow parameters, extrema circle parameters, phase space embedding parameters using delta coordinates, and/or phase space embedding parameters using time delay coordinates). Alternatively or in combination, plots may be qualitatively determined (e.g., STAG plots, T_peak MFM plots, field map animations, pseudo current density arrows, MCD plots, and/or ECD plots) for visual classification (e.g., manually or using computer-based machine vision techniques).

In some embodiments, dipole parameters are determined by measuring of angle and magnitude parameters of a magnetic field map over specified time ranges and at T-peak, which may comprise measurements of Ts/3, Tp, Te/3, etc. For example, dipole parameters (e.g., peak angle, maximum angle, minimum angle, angle dynamics, distance dynamics, and minimum-to-maximum ratio) may be measured from a magnetic field map. As another example, dipole parameters (e.g., peak angle, minimum angle, maximum angle, and angle dynamics) may be measured from a current map. Dipole parameters may be described by, for example, Lim et al., “Detection of non-ST-elevation myocardial infarction using magnetocardiogram: New information from spatiotemporal electrical activation map”, Annals of Medicine, 2009, DOI: 10.1080/07853890903107883, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using an integrated maximum current density (MCD) approach, which comprises determining average measurements of current vectors with maximum magnitude at each time point from a beginning to an end of a T-wave, which may comprise measurements of PCD, Ts, Te, etc. For example, integrated MCD parameters (e.g., magnitude, angle, perimeter, and area), may be measured from a magnetic field map (e.g., of sizes 4x4, 6x6, or 50x50). Integrated MCD parameters may be described by, for example, Zhao et al., “An Integrated Maximum Current Density Approach for Noninvasive Detection of Myocardial Infarction,” IEEE Journal of Biomedical and Health Informatics, 2016, DOI 10.1109/JBHI.2017.2649570, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using an equivalent current density (ECD) approach, which comprises determining average measurements of calculated equivalent current vectors at each time point from a beginning to an end of a T-wave, which may comprise measurements of ECD, Ts, Te, etc. For example, integrated ECD parameters (e.g., magnitude, angle, perimeter, and area), may be measured from a magnetic field map (e.g., of sizes 4x4, 6x6, or 50x50). Integrated ECD parameters may be described by, for example, Zhao et al., “An Integrated Maximum Current Density Approach for Noninvasive Detection of Myocardial Infarction,” IEEE Journal of Biomedical and Health Informatics, 2016, DOI 10.1109/JBHI.2017.2649570, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using a mean pseudo current density (PCD) approach, which comprises determining average measurements of current vector arrows at each time point from a beginning to an end of a T-wave, which may comprise measurements of PCD, Ts, Te, etc. For example, mean PCD parameters (e.g., magnitude, angle, perimeter, and area), may be measured from a magnetic field map (e.g., of sizes 4x4, 6x6, or 50x50). Mean PCD parameters may be described by, for example, Kandori, et al. “A method for detecting myocardial abnormality by using a total current-vector calculated from ST-segment deviation of a magnetocardiogram signal”, Med. Biol. Eng. Comput., 2000, 38, 21-28, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using an isointegral approach, which comprises determining integrated measurements of current vector arrows at each spatial point in either a QRS-complex or a T-wave, which may comprise measurements of PCD, Q, S, Te, etc. For example, isointegral parameters (e.g., QS max integrated current, ST max integrated current diff integrated current, and QS MIC > ST MIC), may be measured from a magnetic field map. Isointegral parameters may be described by, for example, Watanabe, et al. “Magnetocardiography in Early Detection of Electromagnetic Abnormality in Ischemic Heart Disease,” J Arrhythmia, Vol. 24, No. 1, 2008, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using a field map correlation approach, which comprises determining correlations of a magnetic field map at a time point over a range of other times, which may comprise measurements of T_peak, R_peak, etc. For example, field map correlation parameters (e.g., mean values and/or standard deviation values of: T_peak correlation over T_wave, T-peak correlation over R-wave, T-peak correlation over T-wave, and/or R-peak correlation over R-wave), may be measured from 100 Hz low-pass and 20 Hz low-pass filtered data. Field map correlation parameters may be described by, for example, Goernig, et al. “Magnetocardiography Based Spatiotemporal Correlation Analysis is Superior to Conventional ECG Analysis for Identifying Myocardial Injury,” Annals of Biomedical Engineering, Vol. 37, No. 1, 2009, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using an R_peak pegged dipole parameter approach, which comprises determining measurements of angle and/or magnitude parameters of a magnetic field map over specified time ranges, with many angle parameters calculated relative to R-peak field map angle; this may comprise measurements of T_peak, R_peak, etc. For example, R_peak pegged dipole parameters (e.g., R_peak_FMA, T_peak FMA - R_peak_FMA, TT_CAmax, TT_CAmax - R_peak_FMA, and JT_CMD (indicating a change in maximum current magnitude within 20 ms from J_point to T_end)), may be measured from 100 Hz low-pass and 20 Hz low-pass filtered data. R_peak pegged dipole parameters may be described by, for example, Kwon, et al., “Non-Invasive Magnetocardiography for the Early Diagnosis of Coronary Artery Disease in Patients Presenting With Acute Chest Pain”, Circulation Journal, Vol. 74, 2010, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using a pseudo current arrow parameter approach, which comprises determining measurements of parameters for averaged current arrow maps at T-peak of a magnetic field map, using all arrows (global) or any of four map quadrants (Q1, Q2, Q3, Q4); this may comprise measurements of PCD, T_peak, etc. For example, pseudo current arrow parameters may be related to magnitude at T_peak (e.g., mean, variance, kurtosis, and/or skew) and/or angle at T_peak (mean, variance, kurtosis, and/or skew). Pseudo current arrow parameters may be described by, for example, Udovychenko, et al. “Binary Classification of Heart Failures Using k-NN with Various Distance Metrics,” International Journal of Electronics and Telecommunications, Vol. 61, Issue 4, 2015, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using an extrema circle parameter approach, which comprises determining measurements of the positive and negative area ratio and zero contour line curvature within a circle drawn with edges touching positive and negative poles; this may comprise measurements of T_end, T_begin, etc. For example, extrema circle parameters may be related to area ratio and/or contour curvature of a magnetic field map. Extrema circle parameters may be described by, for example, Wu, et al. “Noninvasive Diagnosis of Coronary Artery Disease Using Two Parameters Extracted in an Extrema Circle of Magnetocardiogram,” 35th Annual International Conference of the IEEE EMBS, 2013, which is incorporated by reference herein in its entirety.

In some embodiments, parameters are determined using a phase space embedding parameter approach, which comprises determining reconstructions of a multidimensional phase space approximation of the signal using a delta calculation; this may comprise measurements of delta coordinates, etc. For example, phase space embedding parameters may be related to dimension numbers (M) such as 2, 3, or 6, such as tied binning parameters with 10^M bins and even counts per bin, and a Gaussian mixture model with 20 mixtures.

In some embodiments, parameters are determined using a phase space embedding parameter approach, which comprises determining reconstructions of a multidimensional phase space approximation of the signal using a time delay; this may comprise measurements of delta coordinates, etc. For example, phase space embedding parameters may be related to dimension numbers (M) such as 2, 3, or 6, such as tied binning parameters with 10^M bins and even counts per bin, and a Gaussian mixture model with 20 mixtures.

In some embodiments, STAG plots are generated by plotting the averaged current arrow in basal to apical direction and left to right direction; this may comprise measurements of PCD, S, Te, etc. For example, one or more of the following visual indicators may be assessed: no separation or discontinuity in core, no leftward tail, consistent central location of red core, smooth shape of comet head, core well matched with T-wave, condensed excitation shape and area, and/or compressed in y-axis.

In some embodiments, T-peak MFM plots are generated by plotting the MFM at T-peak. For example, one or more of the following visual indicators may be assessed: compressed dipole, stretched dipole, broken dipole, and/or rotated pole.

In some embodiments, field map animations are generated by assessing the animation of the MFM at T-peak based on certain visual indicators. For example, one or more of the following visual indicators may be assessed: dipole drift, dipole rotation, and/or multiple poles.

In some embodiments, pseudo current density arrows are generated by assessing the pseudo current arrow maps based on certain visual indicators (e.g., to classify the MFM into one of 5 classes). For example, one or more of the following visual indicators may be assessed: dipole present, dipole orientation, majority vector direction, and/or vortex evenness. Pseudo current density arrows may be described by, for example Hailer, et al., “The Value of Magnetocardiography in the Course of Coronary Intervention,” Annals of Noninvasive Electrocardiology, Vol. 10, No. 2, 2005, which is incorporated by reference herein in its entirety.

In some embodiments, MCD plots are generated by assessing the magnetic field maps based on maximum current density vectors. In some embodiments, ECD plots are generated by assessing the magnetic field maps based on equivalent current density vectors. In some embodiments, magnetic field maps are assessed based on one or more of the following visual indicators: Q, S, Ts, Ts/3, Tp, Te/3, Te, and/or Rp.

While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein is employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby. 

What is claimed is: 1-76. (canceled)
 77. A system for determining a presence, an absence, or a likelihood of coronary artery disease in an individual, comprising: (1) a sensing device configured to sense a magnetic field associated with an individual, wherein the device comprises: a. a movable base unit; b. an arm having a proximal end and a distal end, the proximal end being coupled to the moveable base unit by a first j oint, the first j oint configured so that the arm moves relative to the movable base unit with at least one degree of freedom; and c. an array of one or more optically pumped magnetometers coupled to the distal end of the arm, the array of one or more optically pumped magnetometers configured to sense the magnetic field associated with the individual; and (2) a non-transitory computer readable medium encoded with a computer program comprising instructions executable by a processor configured to cause the processor to: i. receive, from the sensing device, a first magnetic field associated with a heart of the individual at a first time; ii. generate a first electromagnetic field map based on the first magnetic field associated with the heart of the individual at the first time; iii. identify a first negative electromagnetic dipole and a first positive electromagnetic dipole in the first electromagnetic field map; iv. receive, from the sensing device, a second magnetic field associated with the heart of the individual at a second time; v. generate a second electromagnetic field map based on the second magnetic field associated with the heart of the individual at the second time; vi. identify a second negative electromagnetic dipole and a second positive electromagnetic dipole in the second electromagnetic field map; vii. determine a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole, and a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; and viii. determine the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on (i) whether the first angle differs from the second angle by at least 100 degrees, or (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.
 78. The system of claim 77, wherein the sensing device comprises a shield configured to shield the device from one or more environmental magnetic fields, wherein the shield is configured to at least partially enclose a portion of a body of the individual which is associated with the magnetic field.
 79. The system of claim 78, wherein the portion of the body of the individual which is associated with the magnetic field is at least a portion of a chest of the individual.
 80. The system of claim 78, wherein the shield comprises two or more layers.
 81. The system of claim 78, wherein the shield comprises permalloy or mumetal.
 82. The system of claim 77, wherein the arm comprises a proximal segment and a distal segment, and wherein a second joint is positioned between the proximal segment and the distal segment and is configured so that the distal segment articulates relative to the proximal segment.
 83. The system of claim 77, wherein the array of one or more optically pumped magnetometers is movably coupled to the distal end of the arm so that the array of the one or more optically pumped magnetometers moves relative to the arm with at least one degree of freedom.
 84. The system of claim 77, wherein the array of one or more optically pumped magnetometers is arranged to match a generalized contour of a portion of a body of the individual.
 85. The system of claim 77, wherein the computer program comprises instructions configured to cause the processor to further filter a sensed magnetic field.
 86. The system of claim 85, further comprising a gradiometer, and wherein the computer program comprises instructions configured to cause the processor to filter the sensed magnetic field by cancelling out a magnetic field sensed by the gradiometer.
 87. The system of claim 85, wherein the computer program comprises instructions configured to cause the processor to filter the sensed magnetic field by subtracting a frequency-based measurement from the magnetic field.
 88. The system of claim 77, wherein the computer program comprises instructions configured to cause the processor to further generate a visual representation of the magnetic field comprising a waveform.
 89. The system of claim 77, wherein the coronary artery disease comprises cardiac myocyte ischemia or cardiac myocyte ischemia with associated epicardial coronary artery disease.
 90. The system of claim 77, wherein the computer program comprises instructions configured to cause the processor to further determine the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on (iii) a parameter selected from the group consisting of: dipole parameters, integrated MCD parameters, integrated ECD parameters, mean PCD parameters, isointegral parameters, field map correlation parameters, R_peak pegged dipole parameters, pseudo current arrow parameters, extrema circle parameters, phase space embedding parameters using delta coordinates, and phase space embedding parameters using time delay coordinates, or (iv) a visualization selected from the group consisting of: a STAG plot, a T_peak MFM plot, a field map animation, pseudo current density arrows, an MCD plot, and an ECD plot.
 91. The system of claim 90, wherein the computer program comprises instructions configured to cause the processor to further determine the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on the parameter or the visualization.
 92. The system of claim 77, wherein the presence of the coronary artery disease in the individual is determined based on a presence of at least one abnormality from among (i) whether the first angle differs from the second angle by at least 100 degrees, (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map, (iii) the parameter, and (iv) the visualization.
 93. A method for determining a presence, an absence, or a likelihood of coronary artery disease in an individual, the method comprising: (a) identifying a first negative electromagnetic dipole and a first positive electromagnetic dipole in a first electromagnetic field map associated with a heart of the individual at a first time; (b) identifying a second negative electromagnetic dipole and second positive electromagnetic dipole in a second electromagnetic field map associated with the heart of the individual at a second time; (c) determining a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole; (d) determining a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; and (e) determining the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on (i) whether the first angle differs from the second angle by at least 100 degrees, or (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.
 94. The method of claim 93, further comprising recording an electrocardiogram of the individual, wherein the first angle comprises a peak R-depolarization angle at the first time, wherein the first time is a time when an R-wave is recorded on the electrocardiogram, wherein the second angle comprises a peak T-repolarization angle at the second time, wherein the second time is a time when a T-wave is recorded on the electrocardiogram.
 95. The method of claim 93, wherein the coronary artery disease comprises an occlusion of the left anterior descending artery.
 96. The method of claim 93, wherein the first angle is determined by determining a first line that passes through both the first negative electromagnetic dipole and the first positive electromagnetic dipole, and determining the angle between the first line and a horizontal axis, and wherein the second angle is determined by determining a second line that passes through both the second negative electromagnetic dipole and the second positive electromagnetic dipole, and determining the angle between the second line and a horizontal axis.
 97. The method of claim 93, wherein the likelihood of the presence of the coronary artery disease in the individual is determined if the first angle differs from the second angle by 100 degrees to 170 degrees.
 98. The method of claim 93, wherein the individual has either a normal electrocardiogram while experiencing chest pain or normal troponin level while experiencing chest pain.
 99. The method of claim 93, wherein the individual has had a positive stress test or abnormal echocardiogram findings.
 100. The method of claim 93, further comprising performing a stress test if the first angle differs from the second angle or there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map.
 101. The method of claim 93, further comprising sensing, at the first time, a first electromagnetic field associated with the heart of the individual, and sensing, at the second time, a second electromagnetic field associated with the heart of the individual, and wherein the first electromagnetic field map comprises a representation of the first electromagnetic field and the second electromagnetic field map comprises a representation of the second electromagnetic field.
 102. The method of claim 93, further comprising determining a likelihood of a presence of a conduction abnormality in the heart of the individual if the first positive electromagnetic dipole and the second negative electromagnetic dipole have a same location or the first negative electromagnetic dipole and the second positive electromagnetic dipole have a same location.
 103. The method of claim 93, further comprising treating the individual with a treatment for coronary artery disease, responsive to determining the likelihood of the presence of the coronary artery disease in the individual.
 104. The method of claim 103, wherein the treatment comprises a daily aspirin regimen, a blood pressure lowering medication, a lipid lowering medication, a cardiac catheterization, or a surgical intervention.
 105. A non-transitory computer-readable medium comprising machine executable code that, upon execution by one or more computer processors, implements a method for determining a presence, an absence, or a likelihood of coronary artery disease in an individual, the method comprising: (a) identifying a first negative electromagnetic dipole and a first positive electromagnetic dipole in a first electromagnetic field map associated with a heart of the individual at a first time; (b) identifying a second negative electromagnetic dipole and second positive electromagnetic dipole in a second electromagnetic field map associated with the heart of the individual at a second time; (c) determining a first angle based on the first negative electromagnetic dipole and the first positive electromagnetic dipole; (d) determining a second angle based on the second negative electromagnetic dipole and the second positive electromagnetic dipole; (e) determining the presence, the absence, or the likelihood of the coronary artery disease in the individual, based at least in part on (i) whether the first angle differs from the second angle by at least 100 degrees, or (ii) whether there is a presence of a third electromagnetic dipole in either the first electromagnetic field map or the second electromagnetic field map. 